ctypes: correct gcc check in test

In case gcc is not available, it will throw exception and test fails.
So catch the exception to skip the test correctly.

======================================================================
ERROR: test_null_dlsym (test.test_ctypes.test_dlerror.TestNullDlsym.test_null_dlsym)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/lib/python3.12/test/test_ctypes/test_dlerror.py", line 61, in test_null_dlsym
    retcode = subprocess.call(["gcc", "--version"],
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/subprocess.py", line 391, in call
    with Popen(*popenargs, **kwargs) as p:
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/subprocess.py", line 1028, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "/usr/lib/python3.12/subprocess.py", line 1963, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: 'gcc'

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

Author: petermarko

Lib/test/test_ctypes/test_dlerror.py

@@ -58,11 +58,14 @@ def test_null_dlsym(self):
         import subprocess
         import tempfile
 
-        retcode = subprocess.call(["gcc", "--version"],
-                                  stdout=subprocess.DEVNULL,
-                                  stderr=subprocess.DEVNULL)
-        if retcode != 0:
+        try:
+            retcode = subprocess.call(["gcc", "--version"],
+                                      stdout=subprocess.DEVNULL,
+                                      stderr=subprocess.DEVNULL)
+        except FileNotFoundError:
             self.skipTest("gcc is missing")
+        if retcode != 0:
+            self.skipTest("gcc --version failed")
 
         pipe_r, pipe_w = os.pipe()
         self.addCleanup(os.close, pipe_r)