[3.12] gh-126554: correct detection of `gcc` for `TestNullDlsym.test_null_dlsym` (GH-129872) (#129945)

gh-126554: correct detection of `gcc` for `TestNullDlsym.test_null_dlsym` (GH-129872)

In case gcc is not available, the test will fail with FileNotFoundError.
So catch the exception to skip the test correctly.
(cherry picked from commit 978211c8a8646b050a8d687ca720f934fcce112c)

Signed-off-by: Peter Marko <peter.marko@siemens.com>
Co-authored-by: Peter Marko <peter.marko@siemens.com>