mesa: skip MultiDrawArrays with primcount == 0

This is the only zero parameter that gallium can't handle.

Reviewed-by: Zoltán Böszörményi <zboszor@gmail.com>
Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8798>

src/mesa/main/draw.c

@@ -830,6 +830,9 @@ _mesa_MultiDrawArrays(GLenum mode, const GLint *first,
        !_mesa_validate_MultiDrawArrays(ctx, mode, count, primcount))
       return;
 
+   if (primcount == 0)
+      return;
+
    struct pipe_draw_info info;
    struct pipe_draw_start_count *draw;