Reenable test_gdb on x86_64
The test was disabled for Python 3.6.4 where it fails currently, but it
completes successfully on Python 3.7. See commit:
Enable also runnig test_gdb on aarch64, as failures are no longer observed.
The bugzilla associated with the reqson why it was disabled is long closed.
See commit: https://src.fedoraproject.org/rpms/python37/c/3b7dcebf399c67228916767bb92e75dd2613baa8