make only valid SkRRects in FuzzPath

As far as I can tell, the attached bugs are self-inflicted wounds.

Bug: skia:8383, oss-fuzz:10378
Change-Id: Ie0bee292982d9e56193b90c04fef5e43bb2e36d4
Reviewed-on: https://skia-review.googlesource.com/156249
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
1 file changed