Fix Gregory patches for bad heptagon geo.

Gregory patch shaders rely on a correct estimate of the maximum valence of the vertices in the mesh.

In the current feature adaptive analysis, we stop at level 1, the center vertex of the heptagon is
never traversed, and its high valence is therefore not recorded. The fix is to take advantage of the
first pass and use the number of vertices in the coarse faces to catch those high-sided non-quads that
would generate high valence vertices that may not be revisited in the second pass.