Log Message:
Enable build of the proxy module, as requested in PR pkg/25517.  Note that
the report asked for a conditional build through a knob, but I can't see a
reason to not enable it by default (so it's now unconditionally built).
Bump PKGREVISION to 3 due to this.

While here, force removal of the modules directory instead of only removing
it when empty.  Any package installing modules must depend on irssi to handle
this shared directory.