x11/xscreensaver: Further clean up

Accidentally pushed an excessive patch for configure.ac which also
included changes done with REINPLACE_CMD, fix this. Check the remaining
patches to configure.ac, turns out none of this is required any more, so
remove it. Therefore also remove USES=autoreconf.

intltool is still required though, it's used to create the
xscreensaver.desktop file. Upstream also ships a broken
po/Makefile.in.in, recreate this by manually calling intltoolize when
NLS is set.

No changes to the resulting package, therefore no PORTREVISION bump.