Allow non-convex paths in Outline#setConvexPath

Bug: 131759669
Test: I5eca77e1a60e484e4e118b7e464a88363c539ca9
Test: Manual - assert no longer fires and app looks normal

The limitation to only support convex paths was due to a limitation
in the old renderer. Today, it is fine to use a concave path. Further,
Skia has changed how it computes complexity - it is more conservative,
so paths which were previously thought to be convex are no longer. We
cannot guarantee that a path will be considered convex (especially
after e.g. rotating it, as in the library in question), so drop the
requirement.

Change-Id: Ice88d0995750e066320cb175a87f8ae70ce3aeed