The macros need to be udpated, since RPM 4.14+ can expand .gem files and
also also provide %{gem_name}.gemspec file used to rebuild the gem.
However, the .gemspec file is not in current directory, but directly in
%{_builddir}.
Move gemified xmlrpc into subpackage.
Move gemified openssl into subpackage.
Tk is removed from stdlib.
Extend 'gem_' macros for pre-release version support.
