utilities: Update gdb script so it works with all python versions

utilities: Update gdb script so it works with all python versions

Newer versions of Python require a different iterator function. This
change will make the iterator classes work with all Python versions.

Adds a fix for python3 as it does not support the long() type.
The fix guaranties the script still works on Python 2.7.

The uKey walker is rather slow on python3, so added a spinner to
indicate we are still busy processing entries.

Fix functions using the iterkeys() function on dictionaries.

Tested-by: solomon <liwei.solomon@gmail.com>
Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>