CI: Only run OpenCL tests when we need to

Like the other drivers, set up rules so we don't run piglit-cl unless we
need to.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/3695
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7330>
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 46e790e..fbd27c8 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1037,6 +1037,7 @@
   extends:
     - .piglit-test
     - .test-cl
+    - .llvmpipe-cl-rules
   variables:
     LP_CL: 1
     LP_NUM_THREADS: 1