mesa/main: fix MultiDrawElements[BaseVertex] validation of primcount
primcount must be a GLsizei as in the signature for MultiDrawElements or bad things can happen. Furthermore, an error should be flagged when primcount is negative. Curiously, this code used to work somewhat correctly even when primcount was negative, because the loop that checks count[i] would iterate out of bounds and almost certainly hit a negative value at some point. Found by an ASAN error in GL45-CTS.gtf32.GL3Tests.draw_elements_base_vertex.draw_elements_base_vertex_primcount Note that the OpenGL spec seems to have s/primcount/drawcount/ at some point, and the code still reflects the old language. v2: provide the correct spec quotes (pointed out by Ian) Cc: mesa-stable@lists.freedesktop.org Reviewed-by: Marek Olšák <marek.olsak@amd.com> (v1) Reviewed-by:Ian Romanick <ian.d.romanick@intel.com> (cherry picked from commit c11dcfb5)