bpo-34007: Skip traceback tests if the Program Counter is not available. (GH-9018)

Sometimes some versions of the shared libraries that are part of the
traceback are compiled in optimised mode and the Program Counter (PC)
is not present, not allowing gdb to walk the frames back. When this
happens, the Python bindings of gdb raise an exception, making the
test impossible to succeed.
(cherry picked from commit f2ef51f8bec525b21e52988880c8a029642795ed)

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>