Makefile generator: add some comments.
Makefile generator: add some comments.

git-svn-id: e7e1075985beda50ea81ac4472467b4f6e91fc78@534 78cadc50-ecff-11dd-a971-7dbc132099af

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