Remove vestigial remnants of GLES2_dbg

These are left over from an early (not finished?) GL debugging
facility that morphed into GLES_trace. Most of the rest of it has
already been removed, these few pieces were still hanging aroung.

Bug: 15028495
Change-Id: Ib7c03eb8d0db30112e1b83e5262bba03006770de