Fix ninja generator to recognize the 'default_target' flag. 
Fix ninja generator to recognize the 'default_target' flag. 

The ninja generator ignore the flag, always using 'all' as the 
default. This is a minor problem for Chrome on Android, which 
specifies the 'All' target to be used by default by setting 
default_target (which works correctly when generating Makefiles). 

BUG=gyp:295
Review URL: https://chromiumcodereview.appspot.com/10916205/

Patch from David Turner <digit@chromium.org>!

git-svn-id: e7e1075985beda50ea81ac4472467b4f6e91fc78@1493 78cadc50-ecff-11dd-a971-7dbc132099af

xin3liang/platform_external_chromium_org_tools_gyp,bpsinc-native/src_tools_gyp,bnoordhuis/gyp,MIPS/external-chromium_org-tools-gyp,okumura/gyp,bnoordhuis/gyp,LazyCodingCat/gyp,mumble-voip/libmumble-gyp,svn2github/gyp,openpeer/webrtc-gyp,turbulenz/gyp,kevinchen3315/gyp-git,trafi/gyp,azunite/gyp_20150930,svn2github/kgyp,okwasi/gyp,LazyCodingCat/gyp,ttyangf/pdfium_gyp,mgamer/gyp,bulldy80/gyp_unofficial,duanhjlt/gyp,mapbox/gyp,bnoordhuis/gyp,yangrongwei/gyp,sport-monkey/GYP,pandaxcl/gyp,bnq4ever/gypgoogle,mapbox/gyp,adblockplus/gyp,IllusionRom-deprecated/android_platform_external_chromium_org_tools_gyp,AOSPU/external_chromium_org_tools_gyp,cysp/gyp,azunite/gyp_20150930,mgamer/gyp,sport-monkey/GYP,cysp/gyp,geekboxzone/lollipop_external_chromium_org_tools_gyp,chromium/gyp,geekboxzone/lollipop_external_chromium_org_tools_gyp,sloanyang/gyp,pandaxcl/gyp,tarc/gyp,turbulenz/gyp,dougbeal/gyp,alexcrichton/gyp,geekboxzone/lollipop_external_chromium_org_tools_gyp,carlTLR/gyp,yjhjstz/gyp,yinquan529/platform-external-chromium_org-tools-gyp,ttyangf/pdfium_gyp,azunite/gyp,okumura/gyp,yjhjstz/gyp,tarc/gyp,mapbox/gyp,svn2github/kgyp,dougbeal/gyp,enkripsi/gyp,erikge/watch_gyp,omasanori/gyp,azunite/gyp,pandaxcl/gyp,carlTLR/gyp,saghul/gyn,ttyangf/pdfium_gyp,channing/gyp,lukeweber/gyp-override,omasanori/gyp,AWhetter/gyp,ttyangf/gyp,bdarnell/gyp,mistydemeo/gyp,alexcrichton/gyp,okwasi/gyp,Phuehvk/gyp,saghul/gyn,svn2github/gyp,mumble-voip/libmumble-gyp,bulldy80/gyp_unofficial,brson/gyp,channing/gyp,saghul/gyn,luvit/gyp,amoikevin/gyp,amoikevin/gyp,LazyCodingCat/gyp,springmeyer/gyp,mumble-voip/libmumble-gyp,pandaxcl/gyp,mapbox/gyp,chromium/gyp,sport-monkey/GYP,enkripsi/gyp,android-ia/platform_external_chromium_org_tools_gyp,Danath/gyp,luvit/gyp,Phuehvk/gyp,pyokagan/gyp,clar/gyp,sdklite/gyp,springmeyer/gyp,mgamer/gyp,sdklite/gyp,erikge/watch_gyp,AWhetter/gyp,springmeyer/gyp,turbulenz/gyp,AWhetter/gyp,tarc/gyp,cchamberlain/gyp,mumble-voip/libmumble-gyp,yjhjstz/gyp,android-ia/platform_external_chromium_org_tools_gyp,cysp/gyp,duanhjlt/gyp,mkrautz/gyp-libmumble,enkripsi/gyp,xin3liang/platform_external_chromium_org_tools_gyp,ttyangf/gyp,lukeweber/gyp-override,Chilledheart/gyp,svn2github/gyp,alexcrichton/gyp,azunite/gyp,cysp/gyp,kevinchen3315/gyp-git,MIPS/external-chromium_org-tools-gyp,svn2github/kgyp,tarc/gyp,omasanori/gyp,msc-/gyp,okwasi/gyp,cchamberlain/gyp,sanyaade-teachings/gyp,trafi/gyp,cchamberlain/gyp,sanyaade-teachings/gyp,okumura/gyp,carlTLR/gyp,enkripsi/gyp,kevinchen3315/gyp-git,Danath/gyp,sloanyang/gyp,clar/gyp,svn2github/gyp,tarc/gyp,Omegaphora/external_chromium_org_tools_gyp,azunite/gyp_20150930,sanyaade-teachings/gyp,bpsinc-native/src_tools_gyp,Phuehvk/gyp,svn2github/kgyp,kevinchen3315/gyp-git,Jack-Q/GYP-copy,pyokagan/gyp,duanhjlt/gyp,mapbox/gyp,Chilledheart/gyp,xin3liang/platform_external_chromium_org_tools_gyp,sport-monkey/GYP,LazyCodingCat/gyp,pyokagan/gyp,Danath/gyp,adblockplus/gyp,Jack-Q/GYP-copy,mistydemeo/gyp,sdklite/gyp,ttyangf/gyp,mkrautz/gyp-libmumble,turbulenz/gyp,mistydemeo/gyp,erikge/watch_gyp,Jack-Q/GYP-copy,yinquan529/platform-external-chromium_org-tools-gyp,adblockplus/gyp,yjhjstz/gyp,Jack-Q/GYP-copy,carlTLR/gyp,amoikevin/gyp,bdarnell/gyp,AOSPU/external_chromium_org_tools_gyp,bnoordhuis/gyp,pyokagan/gyp,bpsinc-native/src_tools_gyp,trafi/gyp,mkrautz/gyp-libmumble,amoikevin/gyp,duanhjlt/gyp,brson/gyp,bnoordhuis/gyp,bnq4ever/gypgoogle,Jack-Q/GYP-copy,IllusionRom-deprecated/android_platform_external_chromium_org_tools_gyp,chromium/gyp,xin3liang/platform_external_chromium_org_tools_gyp,adblockplus/gyp,bpsinc-native/src_tools_gyp,LazyCodingCat/gyp,adblockplus/gyp,msc-/gyp,pyokagan/gyp,svn2github/gyp,bnq4ever/gypgoogle,yjhjstz/gyp,yinquan529/platform-external-chromium_org-tools-gyp,lukeweber/gyp-override,brson/gyp,chromium/gyp,openpeer/webrtc-gyp,erikge/watch_gyp,sloanyang/gyp,ttyangf/pdfium_gyp,channing/gyp,luvit/gyp,MIPS/external-chromium_org-tools-gyp,yangrongwei/gyp,erikge/watch_gyp,Phuehvk/gyp,sanyaade-teachings/gyp,sanyaade-teachings/gyp,sloanyang/gyp,bulldy80/gyp_unofficial,springmeyer/gyp,clar/gyp,okumura/gyp,ttyangf/gyp,dougbeal/gyp,enkripsi/gyp,carlTLR/gyp,Danath/gyp,yinquan529/platform-external-chromium_org-tools-gyp,Omegaphora/external_chromium_org_tools_gyp,mgamer/gyp,brson/gyp,duanhjlt/gyp,Phuehvk/gyp,azunite/gyp_20150930,cchamberlain/gyp,sdklite/gyp,msc-/gyp,bulldy80/gyp_unofficial,clar/gyp,yangrongwei/gyp,cysp/gyp,svn2github/kgyp,amoikevin/gyp,azunite/gyp_20150930,Chilledheart/gyp,dougbeal/gyp,bdarnell/gyp,android-ia/platform_external_chromium_org_tools_gyp,channing/gyp,mistydemeo/gyp,Chilledheart/gyp,IllusionRom-deprecated/android_platform_external_chromium_org_tools_gyp,cchamberlain/gyp,bdarnell/gyp,openpeer/webrtc-gyp,alexcrichton/gyp,springmeyer/gyp,bulldy80/gyp_unofficial,lukeweber/gyp-override,ryfx/gyp,IllusionRom-deprecated/android_platform_external_chromium_org_tools_gyp,openpeer/webrtc-gyp,ryfx/gyp,sport-monkey/GYP,ryfx/gyp,ttyangf/pdfium_gyp,msc-/gyp,AOSPU/external_chromium_org_tools_gyp,azunite/gyp,bnq4ever/gypgoogle,saghul/gyn,chromium/gyp,bnq4ever/gypgoogle,openpeer/webrtc-gyp,pandaxcl/gyp,Omegaphora/external_chromium_org_tools_gyp,Danath/gyp,Omegaphora/external_chromium_org_tools_gyp,yangrongwei/gyp,geekboxzone/lollipop_external_chromium_org_tools_gyp,MIPS/external-chromium_org-tools-gyp,trafi/gyp,luvit/gyp,clar/gyp,turbulenz/gyp,omasanori/gyp,mgamer/gyp,msc-/gyp,AOSPU/external_chromium_org_tools_gyp,Chilledheart/gyp,ryfx/gyp,AWhetter/gyp,AWhetter/gyp,android-ia/platform_external_chromium_org_tools_gyp,ttyangf/gyp,mkrautz/gyp-libmumble,sdklite/gyp,okwasi/gyp,ryfx/gyp,azunite/gyp,saghul/gyn,trafi/gyp,dougbeal/gyp