gitlab-ci: Set the prefix to ./install instead of the DESTDIR.

If we don't set DESTDIR, then the DEFAULT_DRIVER_DIR built into the
libraries is correct and we don't need to use LIBGL_DRIVERS_PATH and
friends for CI usage.  Incidentally, this moves our installed paths
from /builds/anholt/mesa/install/usr/local/lib (for example) to
/builds/anholt/mesa/install/lib for simplicity.

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

.gitlab-ci/meson-build.sh

@@ -17,6 +17,7 @@ fi
 rm -rf _build
 meson _build --native-file=native.file \
       ${CROSS+--cross /cross_file-$CROSS.txt} \
+      -D prefix=`pwd`/install \
       -D libdir=lib \
       -D buildtype=debug \
       -D build-tests=true \
@@ -32,7 +33,7 @@ cd _build
 meson configure
 ninja -j4
 LC_ALL=C.UTF-8 ninja test
-DESTDIR=$PWD/../install ninja install
+ninja install
 cd ..
 
 if test -n "$MESON_SHADERDB"; then

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

@@ -5,8 +5,8 @@ ARTIFACTSDIR=`pwd`/shader-db
 mkdir -p $ARTIFACTSDIR
 export DRM_SHIM_DEBUG=true
 
-LIBDIR=`pwd`/install/usr/local/lib
-export LIBGL_DRIVERS_PATH=$LIBDIR/dri
+LIBDIR=`pwd`/install/lib
+export LD_LIBRARY_PATH=$LIBDIR
 
 cd /usr/local/shader-db