gles2: Make render command queue dynamic.

It now uses a growable linked list that keeps a pool of allocated items for
reuse, and reallocs the vertex array as necessary. Testsprite2 can scale to
20,000 (or more!) draws now without drama.

--HG--
branch : SDL-ryan-batching-renderer
extra : source : a4d56fdc03aa55ae4e04dc1bf7091b5dddc95fae
1 file changed