glsl/tests: Make the tests skip on Android binary execution failures.

We don't have a suitable exe wrapper for running them, and the missing
linker is throwing return code 255 instead of an ENOEXEC.  Catch it and
return skip from the tests.

Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6700>

src/compiler/glsl/glcpp/tests/glcpp_test.py

@@ -76,6 +76,10 @@ def test_output(glcpp, filename, expfile, nl_format='\n'):
         actual, _ = proc.communicate(f.read())
         actual = actual.decode('utf-8')
 
+        if proc.returncode == 255:
+            print("Test returned general error, possibly missing linker")
+            sys.exit(77)
+
     with open(expfile, 'r') as f:
         expected = f.read()