Remove old po/ code for copying .po files from shared directory.

Remove old po/ code for copying .po files from shared directory.

po/Makefile has both old code for copying .po files from a shared
directory /com/share/ftp/gnu/po/maint/glibc (presumably once present
on some GNU server), and new code for downloading them from the
Translation Project.  This patch removes the old code, leading only
the new code.

Tested for x86_64.

	* po/Makefile (linguas): Remove rule and dependencies.
	(linguas.mo): Likewise.
	(.PHONY): Do not depend on linguas and linguas.mo.
	(podir): Remove variable.
	(pofiles): Likewise.
	[$(pofiles)] (%.po): Remove rule.