Fix GrTextureAccess::operator ==
Fix GrTextureAccess::operator ==

compare the textures, correctly intepret memcmp result, don't compare last byte of swizzle array which must be 0.

BUG=895
Review URL: https://codereview.appspot.com/6542048

git-svn-id: e8541e15acce502a64c929015570ad1648e548cd@5605 2bbb7eff-a529-9590-31e7-b0007b416f81

Cue/skia,mrobinson/skia,mrobinson/skia,mrobinson/skia,Cue/skia,metajack/skia,metajack/skia,Cue/skia,metajack/skia,metajack/skia,mrobinson/skia,mrobinson/skia,Cue/skia