Makefile generator: fallback on 'cp' if 'ln' fails.
Makefile generator: fallback on 'cp' if 'ln' fails.

Useful when your build output is on a different file system.

http://code.google.com/p/chromium/issues/detail?id=14785
Patch from Adam Langley.

git-svn-id: e7e1075985beda50ea81ac4472467b4f6e91fc78@526 78cadc50-ecff-11dd-a971-7dbc132099af

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