MacOS.sdk: return newest SDK if requested not found
MacOS.sdk: return newest SDK if requested not found

`MacOS.sdk` and `.sdk_path` will now return the newest installed SDK
instead of nil if called on a system that doesn’t have an SDK for the
currently-installed OS. For example, Xcode 7 on OS X 10.10 does not
include the 10.10 SDK, only the 10.11 SDK; software can be built by
specifying both SDKROOT and MACOSX_DEPLOYMENT_TARGET.

benjaminfrank/homebrew,heinzf/homebrew,mkrapp/homebrew,muellermartin/homebrew,iostat/homebrew2,sjackman/linuxbrew,scpeters/homebrew,slyphon/homebrew,dongcarl/homebrew,jconley/homebrew,Homebrew/linuxbrew,reelsense/homebrew,Red54/homebrew,dongcarl/homebrew,pdxdan/homebrew,liamstask/homebrew,geoff-codes/homebrew,dongcarl/homebrew,gicmo/homebrew,heinzf/homebrew,skatsuta/homebrew,codeout/homebrew,ablyler/homebrew,reelsense/linuxbrew,influxdb/homebrew,joshua-rutherford/homebrew,davydden/linuxbrew,influxdata/homebrew,dalanmiller/homebrew,hyuni/homebrew,kenips/homebrew,pcottle/homebrew,gicmo/homebrew,hakamadare/homebrew,marcwebbie/homebrew,razamatan/homebrew,filcab/homebrew,hanxue/homebrew,dickeyxxx/homebrew,pcottle/homebrew,josa42/homebrew,ExtremeMan/homebrew,manphiz/homebrew,jamer/homebrew,kenips/homebrew,cprecioso/homebrew,danieroux/homebrew,OJFord/homebrew,jsjohnst/homebrew,Linuxbrew/linuxbrew,pdxdan/homebrew,deorth/homebrew,dalanmiller/homebrew,scorphus/homebrew,keith/homebrew,zhipeng-jia/homebrew,Chilledheart/homebrew,SuperNEMO-DBD/cadfaelbrew,haihappen/homebrew,drbenmorgan/linuxbrew,keith/homebrew,frodeaa/homebrew,teslamint/homebrew,princeofdarkness76/homebrew,filcab/homebrew,hongkongkiwi/homebrew,jamer/homebrew,heinzf/homebrew,kevinastone/homebrew,totalvoidness/homebrew,adamliter/homebrew,SuperNEMO-DBD/cadfaelbrew,mactkg/homebrew,miketheman/homebrew,kodabb/homebrew,gicmo/homebrew,dunn/homebrew,mmizutani/homebrew,elyscape/homebrew,thinker0/homebrew,marcwebbie/homebrew,kodabb/homebrew,hongkongkiwi/homebrew,nandub/homebrew,bukzor/linuxbrew,BrewTestBot/homebrew,pcottle/homebrew,esamson/homebrew,manphiz/homebrew,ebouaziz/linuxbrew,nelstrom/homebrew,Asuranceturix/homebrew,base10/homebrew,chadcatlett/homebrew,adamliter/homebrew,Chilledheart/homebrew,cosmo0920/homebrew,liamstask/homebrew,jiashuw/homebrew,saketkc/linuxbrew,3van/homebrew,skinny-framework/homebrew,totalvoidness/homebrew,kenips/homebrew,polishgeeks/homebrew,royhodgman/homebrew,tschoonj/homebrew,TaylorMonacelli/homebrew,ablyler/homebrew,koraktor/homebrew,alebcay/homebrew,blogabe/homebrew,georgschoelly/homebrew,influxdb/homebrew,georgschoelly/homebrew,ralic/homebrew,marcwebbie/homebrew,koraktor/homebrew,youtux/homebrew,jsjohnst/homebrew,esamson/homebrew,SteveClement/homebrew,emcrisostomo/homebrew,Homebrew/homebrew,ybott/homebrew,eighthave/homebrew,DoomHammer/linuxbrew,OJFord/homebrew,megahall/homebrew,alebcay/homebrew,feelpp/homebrew,redpen-cc/homebrew,xcezx/homebrew,redpen-cc/homebrew,base10/homebrew,polishgeeks/homebrew,dericed/homebrew,utzig/homebrew,reelsense/homebrew,Homebrew/linuxbrew,sakra/homebrew,saketkc/linuxbrew,razamatan/homebrew,ento/homebrew,tutumcloud/homebrew,knpwrs/homebrew,drewwells/homebrew,sjackman/linuxbrew,dgageot/homebrew,apjanke/homebrew,AlexejK/homebrew,yangj1e/homebrew,ablyler/homebrew,lrascao/homebrew,dalanmiller/homebrew,nelstrom/homebrew,bukzor/linuxbrew,ear/homebrew,johanhammar/homebrew,jconley/homebrew,afh/homebrew,MoSal/homebrew,Red54/homebrew,MartinDelille/homebrew,SteveClement/homebrew,dutchcoders/homebrew,mactkg/homebrew,bukzor/linuxbrew,davydden/linuxbrew,SuperNEMO-DBD/cadfaelbrew,joshua-rutherford/homebrew,sferik/homebrew,thinker0/homebrew,joshfriend/homebrew,feelpp/homebrew,knpwrs/homebrew,ybott/homebrew,BrewTestBot/homebrew,optikfluffel/homebrew,dutchcoders/homebrew,zchee/homebrew,gnubila-france/linuxbrew,royhodgman/homebrew,afh/homebrew,mkrapp/homebrew,dalanmiller/homebrew,keith/homebrew,sakra/homebrew,sferik/homebrew,deorth/homebrew,dkotvan/homebrew,iandennismiller/homebrew,hanxue/homebrew,sferik/homebrew,skatsuta/homebrew,yangj1e/homebrew,teslamint/homebrew,gawbul/homebrew,jsjohnst/homebrew,danieroux/homebrew,dplarson/homebrew,TaylorMonacelli/homebrew,mobileoverlord/homebrew-1,teslamint/homebrew,theeternalsw0rd/homebrew,Linuxbrew/linuxbrew,optikfluffel/homebrew,koraktor/homebrew,nelstrom/homebrew,thinker0/homebrew,reelsense/linuxbrew,menivaitsi/homebrew,slyphon/homebrew,chadcatlett/homebrew,princeofdarkness76/homebrew,yangj1e/homebrew,Asuranceturix/homebrew,brunchboy/homebrew,jab/homebrew,jsjohnst/homebrew,jarrettmeyer/homebrew,zchee/homebrew,ralic/homebrew,muellermartin/homebrew,feelpp/homebrew,drbenmorgan/linuxbrew,ryanfb/homebrew,iostat/homebrew2,megahall/homebrew,muellermartin/homebrew,cchacin/homebrew,elgertam/homebrew,royhodgman/homebrew,ehamberg/homebrew,koraktor/homebrew,ebouaziz/linuxbrew,hanxue/homebrew,adamliter/homebrew,youtux/homebrew,tschoonj/homebrew,liamstask/homebrew,AGWA-forks/homebrew,feelpp/homebrew,dplarson/homebrew,heinzf/homebrew,gnubila-france/linuxbrew,filcab/homebrew,Angeldude/linuxbrew,MoSal/homebrew,theeternalsw0rd/homebrew,ExtremeMan/homebrew,dunn/homebrew,decors/homebrew,iandennismiller/homebrew,yazuuchi/homebrew,jamer/homebrew,ExtremeMan/homebrew,elgertam/homebrew,booi/homebrew,utzig/homebrew,base10/homebrew,totalvoidness/homebrew,miketheman/homebrew,skinny-framework/homebrew,optikfluffel/homebrew,kodabb/homebrew,drbenmorgan/linuxbrew,joshua-rutherford/homebrew,reelsense/homebrew,hongkongkiwi/homebrew,galaxy001/homebrew,lvicentesanchez/homebrew,Chilledheart/homebrew,tschoonj/homebrew,dongcarl/homebrew,liamstask/homebrew,georgschoelly/homebrew,recruit-tech/homebrew,yazuuchi/homebrew,iostat/homebrew2,vigo/homebrew,georgschoelly/homebrew,jarrettmeyer/homebrew,iandennismiller/homebrew,reelsense/linuxbrew,osimola/homebrew,princeofdarkness76/homebrew,megahall/homebrew,cosmo0920/homebrew,deorth/homebrew,frodeaa/homebrew,ilovezfs/homebrew,marcwebbie/homebrew,AGWA-forks/homebrew,jab/homebrew,dgageot/homebrew,retrography/homebrew,blogabe/homebrew,skinny-framework/homebrew,cchacin/homebrew,getgauge/homebrew,mmizutani/homebrew,dutchcoders/homebrew,getgauge/homebrew,dkotvan/homebrew,MartinDelille/homebrew,ehamberg/homebrew,LinusU/homebrew,miketheman/homebrew,pdxdan/homebrew,3van/homebrew,sometimesfood/homebrew,zhipeng-jia/homebrew,eighthave/homebrew,josa42/homebrew,TaylorMonacelli/homebrew,jab/homebrew,totalvoidness/homebrew,getgauge/homebrew,zeha/homebrew,AGWA-forks/homebrew,Homebrew/homebrew,Linuxbrew/linuxbrew,hyuni/homebrew,decors/homebrew,AlexejK/homebrew,petere/homebrew,polishgeeks/homebrew,emcrisostomo/homebrew,miketheman/homebrew,menivaitsi/homebrew,emcrisostomo/homebrew,alebcay/homebrew,retrography/homebrew,recruit-tech/homebrew,jiashuw/homebrew,blogabe/homebrew,ilovezfs/homebrew,mmizutani/homebrew,scpeters/homebrew,cprecioso/homebrew,sjackman/linuxbrew,sometimesfood/homebrew,decors/homebrew,jab/homebrew,influxdata/homebrew,quantumsteve/homebrew,petere/homebrew,petere/homebrew,gicmo/homebrew,afh/homebrew,MartinDelille/homebrew,ybott/homebrew,influxdata/homebrew,hyuni/homebrew,princeofdarkness76/homebrew,DoomHammer/linuxbrew,bigbes/homebrew,manphiz/homebrew,bigbes/homebrew,MartinDelille/homebrew,Gasol/homebrew,ilovezfs/homebrew,DoomHammer/linuxbrew,afh/homebrew,OJFord/homebrew,SuperNEMO-DBD/cadfaelbrew,ilovezfs/homebrew,elyscape/homebrew,ento/homebrew,treyharris/homebrew,saketkc/linuxbrew,recruit-tech/homebrew,polishgeeks/homebrew,influxdata/homebrew,zeha/homebrew,eighthave/homebrew,bigbes/homebrew,hongkongkiwi/homebrew,gnubila-france/linuxbrew,michaKFromParis/homebrew-sparks,redpen-cc/homebrew,scpeters/homebrew,apjanke/homebrew,ehamberg/homebrew,influxdb/homebrew,retrography/homebrew,ralic/homebrew,ebouaziz/linuxbrew,yangj1e/homebrew,ehamberg/homebrew,ear/homebrew,jiashuw/homebrew,decors/homebrew,BrewTestBot/homebrew,Homebrew/linuxbrew,Homebrew/homebrew,drewwells/homebrew,benjaminfrank/homebrew,ryanfb/homebrew,royhodgman/homebrew,mobileoverlord/homebrew-1,skatsuta/homebrew,BrewTestBot/homebrew,dickeyxxx/homebrew,mactkg/homebrew,vigo/homebrew,booi/homebrew,pcottle/homebrew,quantumsteve/homebrew,benjaminfrank/homebrew,utzig/homebrew,influxdb/homebrew,SteveClement/homebrew,base10/homebrew,gnubila-france/linuxbrew,joshfriend/homebrew,ear/homebrew,zeha/homebrew,sakra/homebrew,Linuxbrew/linuxbrew,scorphus/homebrew,drbenmorgan/linuxbrew,tutumcloud/homebrew,menivaitsi/homebrew,iandennismiller/homebrew,sferik/homebrew,josa42/homebrew,codeout/homebrew,jamer/homebrew,xcezx/homebrew,yazuuchi/homebrew,getgauge/homebrew,ebouaziz/linuxbrew,eighthave/homebrew,sometimesfood/homebrew,kevinastone/homebrew,SteveClement/homebrew,nandub/homebrew,skinny-framework/homebrew,ExtremeMan/homebrew,jconley/homebrew,utzig/homebrew,apjanke/homebrew,gawbul/homebrew,razamatan/homebrew,johanhammar/homebrew,scorphus/homebrew,dutchcoders/homebrew,haihappen/homebrew,dplarson/homebrew,galaxy001/homebrew,Gasol/homebrew,pcottle/homebrew,menivaitsi/homebrew,benjaminfrank/homebrew,kevinastone/homebrew,elgertam/homebrew,johanhammar/homebrew,xcezx/homebrew,geoff-codes/homebrew,megahall/homebrew,reelsense/homebrew,nandub/homebrew,quantumsteve/homebrew,knpwrs/homebrew,yumitsu/homebrew,tutumcloud/homebrew,zchee/homebrew,Asuranceturix/homebrew,skatsuta/homebrew,geoff-codes/homebrew,thinker0/homebrew,frodeaa/homebrew,arnested/homebrew,joshua-rutherford/homebrew,recruit-tech/homebrew,dericed/homebrew,arnested/homebrew,DoomHammer/linuxbrew,dplarson/homebrew,razamatan/homebrew,lrascao/homebrew,brunchboy/homebrew,haihappen/homebrew,lvicentesanchez/homebrew,zhipeng-jia/homebrew,muellermartin/homebrew,dgageot/homebrew,vigo/homebrew,yazuuchi/homebrew,arnested/homebrew,Angeldude/linuxbrew,slyphon/homebrew,esamson/homebrew,lvicentesanchez/homebrew,scpeters/homebrew,dericed/homebrew,Gasol/homebrew,LinusU/homebrew,kodabb/homebrew,ear/homebrew,bigbes/homebrew,optikfluffel/homebrew,elyscape/homebrew,cprecioso/homebrew,manphiz/homebrew,Angeldude/linuxbrew,ybott/homebrew,esamson/homebrew,zhipeng-jia/homebrew,ryanfb/homebrew,sjackman/linuxbrew,apjanke/homebrew,jconley/homebrew,AGWA-forks/homebrew,filcab/homebrew,quantumsteve/homebrew,mactkg/homebrew,Homebrew/homebrew,cscetbon/homebrew,sakra/homebrew,cscetbon/homebrew,cprecioso/homebrew,AlexejK/homebrew,youtux/homebrew,bukzor/linuxbrew,chadcatlett/homebrew,elyscape/homebrew,hanxue/homebrew,ento/homebrew,frodeaa/homebrew,yumitsu/homebrew,nelstrom/homebrew,blogabe/homebrew,elgertam/homebrew,dkotvan/homebrew,redpen-cc/homebrew,OJFord/homebrew,ablyler/homebrew,geoff-codes/homebrew,keith/homebrew,hakamadare/homebrew,gawbul/homebrew,yumitsu/homebrew,tutumcloud/homebrew,drewwells/homebrew,teslamint/homebrew,iostat/homebrew2,jiashuw/homebrew,hakamadare/homebrew,LinusU/homebrew,cchacin/homebrew,nandub/homebrew,MoSal/homebrew,jarrettmeyer/homebrew,youtux/homebrew,cchacin/homebrew,michaKFromParis/homebrew-sparks,brunchboy/homebrew,retrography/homebrew,dkotvan/homebrew,cosmo0920/homebrew,jarrettmeyer/homebrew,zchee/homebrew,codeout/homebrew,mmizutani/homebrew,osimola/homebrew,knpwrs/homebrew,haihappen/homebrew,Angeldude/linuxbrew,michaKFromParis/homebrew-sparks,treyharris/homebrew,galaxy001/homebrew,arnested/homebrew,cosmo0920/homebrew,kenips/homebrew,dunn/homebrew,lvicentesanchez/homebrew,MoSal/homebrew,xcezx/homebrew,emcrisostomo/homebrew,galaxy001/homebrew,Homebrew/linuxbrew,danieroux/homebrew,osimola/homebrew,hyuni/homebrew,ento/homebrew,treyharris/homebrew,hakamadare/homebrew,TaylorMonacelli/homebrew,AlexejK/homebrew,SteveClement/homebrew,treyharris/homebrew,Gasol/homebrew,johanhammar/homebrew,alebcay/homebrew,codeout/homebrew,sometimesfood/homebrew,dericed/homebrew,slyphon/homebrew,petere/homebrew,vigo/homebrew,drewwells/homebrew,cscetbon/homebrew,scorphus/homebrew,kevinastone/homebrew,Chilledheart/homebrew,dunn/homebrew,zeha/homebrew,ryanfb/homebrew,davydden/linuxbrew,Asuranceturix/homebrew,theeternalsw0rd/homebrew,Red54/homebrew,osimola/homebrew,3van/homebrew,tschoonj/homebrew,ralic/homebrew,pdxdan/homebrew,3van/homebrew,Asuranceturix/homebrew,adamliter/homebrew,mkrapp/homebrew,danieroux/homebrew,Red54/homebrew,theeternalsw0rd/homebrew,reelsense/linuxbrew,dgageot/homebrew,booi/homebrew,saketkc/linuxbrew,lrascao/homebrew,mobileoverlord/homebrew-1,dickeyxxx/homebrew,joshfriend/homebrew,mobileoverlord/homebrew-1,brunchboy/homebrew,dickeyxxx/homebrew,LinusU/homebrew,davydden/linuxbrew