Remove unused variable to fix warning on Windows:   src\core\SkBlitter_ARGB32.cpp(362) : warning C4101: 'alpha32' : unreferenced local variable
Remove unused variable to fix warning on Windows:
  src\core\SkBlitter_ARGB32.cpp(362) : warning C4101: 'alpha32' : unreferenced local variable


git-svn-id: e8541e15acce502a64c929015570ad1648e548cd@278 2bbb7eff-a529-9590-31e7-b0007b416f81

metajack/skia,hbwhlklive/color-emoji.skia,Hankuo/color-emoji.skia,Hankuo/color-emoji.skia,MatChung/color-emoji.skia,Frankie-666/color-emoji.skia,MatChung/color-emoji.skia,MatChung/color-emoji.skia,MatChung/color-emoji.skia,Cue/skia,Hankuo/color-emoji.skia,MatChung/color-emoji.skia,Frankie-666/color-emoji.skia,mrobinson/skia,Frankie-666/color-emoji.skia,Frankie-666/color-emoji.skia,mrobinson/skia,mrobinson/skia,hbwhlklive/color-emoji.skia,hbwhlklive/color-emoji.skia,Frankie-666/color-emoji.skia,mrobinson/skia,Hankuo/color-emoji.skia,hbwhlklive/color-emoji.skia,Cue/skia,mrobinson/skia,Hankuo/color-emoji.skia,Cue/skia,hbwhlklive/color-emoji.skia,hbwhlklive/color-emoji.skia,metajack/skia,metajack/skia,metajack/skia,Cue/skia,Hankuo/color-emoji.skia,Frankie-666/color-emoji.skia,MatChung/color-emoji.skia