Fix msvs-ninja clean build command / target.
Fix msvs-ninja clean build command / target.

Currently the clean command is specified as

ninja.exe -C $(OutDir) -t clean $(ProjectName)

but _BuildCommandLineForRuleRaw sees 'clean' as a path, calling _FixPath on it.
This is not a problem for Chromium because it does not set --generator-output.
As a result fixpath_prefix is None and no adjustment is made to paths.
Skia, however, does set --generator-output, and so an attempt is made to adjust
paths with _FixPath. As a result, with Skia the msvs 'Clean' target contains

ninja.exe -C $(OutDir) -t ../../gyp/clean $(ProjectName)

This change changes the command to

ninja.exe -C $(OutDir) -tclean $(ProjectName)

which it valid for ninja, but _BuildCommandLineForRuleRaw will not _FixPath it.

BUG=skia:2439
R=sbaig1@bloomberg.net

Review URL: https://codereview.chromium.org/314163003

git-svn-id: e7e1075985beda50ea81ac4472467b4f6e91fc78@1929 78cadc50-ecff-11dd-a971-7dbc132099af

LazyCodingCat/gyp,pandaxcl/gyp,springmeyer/gyp,trafi/gyp,cchamberlain/gyp,tarc/gyp,cysp/gyp,AOSPU/external_chromium_org_tools_gyp,xin3liang/platform_external_chromium_org_tools_gyp,bnoordhuis/gyp,chromium/gyp,cchamberlain/gyp,enkripsi/gyp,sdklite/gyp,turbulenz/gyp,turbulenz/gyp,sanyaade-teachings/gyp,xin3liang/platform_external_chromium_org_tools_gyp,Jack-Q/GYP-copy,yjhjstz/gyp,Omegaphora/external_chromium_org_tools_gyp,Phuehvk/gyp,Chilledheart/gyp,bpsinc-native/src_tools_gyp,carlTLR/gyp,azunite/gyp,ttyangf/pdfium_gyp,clar/gyp,msc-/gyp,LazyCodingCat/gyp,ryfx/gyp,ttyangf/gyp,azunite/gyp,bnq4ever/gypgoogle,carlTLR/gyp,pandaxcl/gyp,yjhjstz/gyp,AWhetter/gyp,mapbox/gyp,openpeer/webrtc-gyp,LazyCodingCat/gyp,geekboxzone/lollipop_external_chromium_org_tools_gyp,Danath/gyp,clar/gyp,Chilledheart/gyp,sport-monkey/GYP,ryfx/gyp,tarc/gyp,bulldy80/gyp_unofficial,adblockplus/gyp,Chilledheart/gyp,bulldy80/gyp_unofficial,android-ia/platform_external_chromium_org_tools_gyp,geekboxzone/lollipop_external_chromium_org_tools_gyp,duanhjlt/gyp,sanyaade-teachings/gyp,android-ia/platform_external_chromium_org_tools_gyp,erikge/watch_gyp,bnq4ever/gypgoogle,tarc/gyp,msc-/gyp,erikge/watch_gyp,AOSPU/external_chromium_org_tools_gyp,turbulenz/gyp,Omegaphora/external_chromium_org_tools_gyp,turbulenz/gyp,trafi/gyp,sanyaade-teachings/gyp,dougbeal/gyp,bnq4ever/gypgoogle,sport-monkey/GYP,sdklite/gyp,bnoordhuis/gyp,springmeyer/gyp,azunite/gyp,azunite/gyp_20150930,sport-monkey/GYP,mapbox/gyp,android-ia/platform_external_chromium_org_tools_gyp,AWhetter/gyp,msc-/gyp,Danath/gyp,bnq4ever/gypgoogle,duanhjlt/gyp,ryfx/gyp,cchamberlain/gyp,Omegaphora/external_chromium_org_tools_gyp,carlTLR/gyp,sdklite/gyp,bulldy80/gyp_unofficial,Jack-Q/GYP-copy,erikge/watch_gyp,amoikevin/gyp,tarc/gyp,mgamer/gyp,erikge/watch_gyp,springmeyer/gyp,adblockplus/gyp,azunite/gyp_20150930,Phuehvk/gyp,sanyaade-teachings/gyp,clar/gyp,azunite/gyp_20150930,sport-monkey/GYP,android-ia/platform_external_chromium_org_tools_gyp,springmeyer/gyp,ttyangf/pdfium_gyp,AOSPU/external_chromium_org_tools_gyp,adblockplus/gyp,saghul/gyn,dougbeal/gyp,yjhjstz/gyp,ttyangf/pdfium_gyp,tarc/gyp,ttyangf/pdfium_gyp,bnoordhuis/gyp,Phuehvk/gyp,sport-monkey/GYP,Omegaphora/external_chromium_org_tools_gyp,enkripsi/gyp,bnoordhuis/gyp,amoikevin/gyp,cchamberlain/gyp,AWhetter/gyp,LazyCodingCat/gyp,dougbeal/gyp,bulldy80/gyp_unofficial,mgamer/gyp,LazyCodingCat/gyp,duanhjlt/gyp,sdklite/gyp,ttyangf/gyp,ttyangf/pdfium_gyp,erikge/watch_gyp,clar/gyp,ryfx/gyp,Jack-Q/GYP-copy,enkripsi/gyp,geekboxzone/lollipop_external_chromium_org_tools_gyp,pandaxcl/gyp,bnoordhuis/gyp,azunite/gyp,AWhetter/gyp,saghul/gyn,cysp/gyp,saghul/gyn,ttyangf/gyp,mgamer/gyp,amoikevin/gyp,trafi/gyp,openpeer/webrtc-gyp,saghul/gyn,duanhjlt/gyp,adblockplus/gyp,azunite/gyp,Phuehvk/gyp,mapbox/gyp,AWhetter/gyp,chromium/gyp,bpsinc-native/src_tools_gyp,cysp/gyp,mapbox/gyp,bulldy80/gyp_unofficial,amoikevin/gyp,AOSPU/external_chromium_org_tools_gyp,mgamer/gyp,Jack-Q/GYP-copy,msc-/gyp,sdklite/gyp,pandaxcl/gyp,cchamberlain/gyp,enkripsi/gyp,trafi/gyp,saghul/gyn,carlTLR/gyp,chromium/gyp,yjhjstz/gyp,Jack-Q/GYP-copy,geekboxzone/lollipop_external_chromium_org_tools_gyp,openpeer/webrtc-gyp,xin3liang/platform_external_chromium_org_tools_gyp,azunite/gyp_20150930,turbulenz/gyp,dougbeal/gyp,pandaxcl/gyp,ttyangf/gyp,bnq4ever/gypgoogle,cysp/gyp,adblockplus/gyp,dougbeal/gyp,xin3liang/platform_external_chromium_org_tools_gyp,ryfx/gyp,openpeer/webrtc-gyp,Phuehvk/gyp,bpsinc-native/src_tools_gyp,Danath/gyp,mapbox/gyp,Chilledheart/gyp,chromium/gyp,openpeer/webrtc-gyp,cysp/gyp,Chilledheart/gyp,enkripsi/gyp,sanyaade-teachings/gyp,Danath/gyp,azunite/gyp_20150930,duanhjlt/gyp,trafi/gyp,ttyangf/gyp,msc-/gyp,amoikevin/gyp,bpsinc-native/src_tools_gyp,mgamer/gyp,yjhjstz/gyp,clar/gyp,Danath/gyp,springmeyer/gyp,chromium/gyp,carlTLR/gyp