gitlab-ci: Add a shader-db run using v3d on drm-shim.

This provides significant compiler coverage during CI at a fairly low
cost in CPU time (~17s per thread for 4 threads on
gst-gitlab-htz-runner3).

I'm leaving wget in the docker image, as once this is in master I'm
planning on having an automatic shader-db comparison between master
and the branch included in the artifacts.  I also haven't done
freedreno yet, because it has some races when run in multithreaded
mode that I'm still tracking down.

Reviewed-by: Eric Engestrom <eric@engestrom.ch>

.gitlab-ci/run-shader-db.sh

@@ -0,0 +1,15 @@
+set -e
+set -v
+
+ARTIFACTSDIR=`pwd`/shader-db
+mkdir -p $ARTIFACTSDIR
+export DRM_SHIM_DEBUG=true
+
+LIBDIR=`pwd`/install/usr/local/lib
+export LIBGL_DRIVERS_PATH=$LIBDIR/dri
+
+cd /usr/local/shader-db
+
+env LD_PRELOAD=$LIBDIR/libv3d_noop_drm_shim.so \
+    ./run -j 4 ./shaders \
+        > $ARTIFACTSDIR/v3d-shader-db.txt