Remove SkLCGRandom. We already decided the new one was better, which is
why we wrote the new SkRandom.
Convert GMs that were using SkLCGRandom to use the improved SkRandom.
Motivated by the fact that these GMs draw differently on some runs. We
believe this to be a result of using the old SkLCGRandom.
Add each of the tests that were using SkLCGRandom to ignore-tests.txt,
since we expect they'll draw differently using SkRandom.
Move a trimmed down version of SkLCGRandom into SkDiscretePathEffect.
In order to preserve the old behavior, trim down SkLCGRandom to only
the methods used by SkDiscretePathEffect, and hide it in
SkDiscretePathEffect's cpp file.
BUG=skia:3241
Review URL: https://codereview.chromium.org/805963002
f9d610179d