Running renderer tests using mesa's software rendering has a tendency
to misbehave (esp. on tinderboxes) and does not reflect usage on real
hardware.

These are auto-skipped if mesa[-gles2] and perhaps [-llvm], but pretend
we lack support even if conditions are met.

https://bugs.gentoo.org/903295
https://bugs.gentoo.org/911320
https://bugs.gentoo.org/911367
--- a/tests/framework/src/options.rs
+++ b/tests/framework/src/options.rs
@@ -170,2 +170,3 @@
         if let Some(render) = &self.with_renderer {
+            if check_renderer { return false; }
             // If we don't actually want to check the renderer (ie we're just listing potential tests),