limit addEndMoveSpans loop in pathops

Prevent addEndMoveSpans from looping
forever and abort with an error
if the loop count is crazy big.

R=kjlubick@google.com
BUG=684553

Change-Id: I16c250c0b2f88534f809aba17a18081aea4e1f44
Reviewed-on: https://skia-review.googlesource.com/9458
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Cary Clark <caryclark@google.com>
2 files changed