vrend: Don't try to set SSBOs when no location is given

As suggested by Lepton

Fixes 57a4e9498a
vrend: get rid of glShaderStorageBlockBinding

Closes: #229

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Lepton Wu <lepton@chromium.org>

src/vrend_renderer.c

@@ -4342,6 +4342,9 @@ static void vrend_draw_bind_ssbo_shader(struct vrend_sub_context *sub_ctx, int s
    if (!has_feature(feat_ssbo))
       return;
 
+   if (!sub_ctx->prog->ssbo_used_mask[shader_type])
+      return;
+
    if (!sub_ctx->ssbo_used_mask[shader_type])
       return;