glsl/tests/warnings-test: error out if glsl_compiler is missing

... or non-executable, in particular.

v2: use test -x (Eric)

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org> (v1)
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>

src/compiler/glsl/tests/warnings-test.sh

@@ -6,6 +6,11 @@ compiler=./glsl_compiler
 total=0
 pass=0
 
+if [ ! -x "$compiler" ]; then
+    echo "Could not find glsl_compiler. Ensure that it is build via make check"
+    exit 1
+fi
+
 echo "====== Testing compilation output ======"
 for test in `find . -iname '*.vert'`; do
     echo -n "Testing $test..."