fix fuzz asserts triggered by old fuzzes

fuzz fixes

Fixes from running all pathops fuzz testson ToT.

R=kjlubick@google.com
BUG=skia:

Change-Id: Ic84b868a0cc53993e6561bc95fa364218bc3aa34
Reviewed-on: https://skia-review.googlesource.com/7325
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Cary Clark <caryclark@google.com>
3 files changed