ninja: make cross-compilation use $CC/$CXX for the target compiler Fixed mac bot issue.
ninja: make cross-compilation use $CC/$CXX for the target compiler
Fixed mac bot issue.

Took over from http://codereview.chromium.org/9649016/ 

BUG=140900
TEST=set CC/CXX to cross-compiler, set GYP_CROSSCOMPILE to 1, run gyp, ninja chrome.



git-svn-id: e7e1075985beda50ea81ac4472467b4f6e91fc78@1458 78cadc50-ecff-11dd-a971-7dbc132099af

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