tests: fix assert-msg-test with custom gdbinit

As recommended by GDB on Fedora, I have "set debuginfod enabled on" in
my .gdbinit. However, this make assert-msg-test time out.

Let's ignore user gdbinit for the test, as this shouldn't be required
and can easily break the test.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

glib/tests/assert-msg-test.py

@@ -102,7 +102,7 @@ class TestAssertMessage(unittest.TestCase):
         if self.__gdb is None:
             return Result(None, "", "")
 
-        argv = ["gdb", "--batch"]
+        argv = ["gdb", "-n", "--batch"]
         argv.extend(args)
         print("Running:", argv)