* lang/python/Makefile.am: Now that gpg2 has been renamed back to gpg
  and gpg1 is semi-deprecated, we should check what the actual gpg
  binary is with gpgconf and use that rather than make assumptions per
  system.
* Also, it means less worry if gpg3 is ever a thing.  (Trust me, I
  remember the Python 1 to 2 transition as well as the current 2 to 3
  transition).  ;)