Make skdiff use enumeration of result types instead of separate booleans for each result type.

This is one step on the way to a more robust version of skdiff that we can use to address http://code.google.com/p/skia/issues/detail?id=473 ('PDF gradtext gm image results are nondeterministic')

I have confirmed that skdiff results will not change, using tools/tests/run.sh.
Review URL: https://codereview.appspot.com/6208063

git-svn-id: http://skia.googlecode.com/svn/trunk@3972 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed