Avoid int64 overflow in SkClampRange

Update sk_64_smul_check to detect the numeric_limits<int64_t>::min()
case (which cannot be safely passed to SkTAbs), and fail.

BUG=skia:6019
R=reed@google.com,mtklein@google.com

Change-Id: I5f252be7e9377d3261f992b53f2b893899cbe960
Reviewed-on: https://skia-review.googlesource.com/5863
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>
1 file changed