mplayer, *xine: Complete on *.mts (Debian: #759219)
rpmbuild: Complete *.spec on --clean (RedHat: #1132959)
rpmbuild: Complete *.spec on --nobuild
Comment update
_completion_loader: Set empty command to _EmptycmD_ for cross version compat

bash 4.3 gives us _EmptycmD_ for empty commands, while earlier
versions give us the empty string; set it to _EmptycmD_ for those as
well for consistency.
_init_completion: Handle cword < 0 (LP: #1289597)

Previously only bash 4.3 seemed to provoke this, but now with the
empty command consistency tweak it occurs with earlier as well.
pigz, unpigz: Handle *.zz