First off, afaict, xc16x support has never been merged into gcc.
Upstream merge isn't strictly required for new ports, but it seems
like people should merge eventually in some shape, and considering
the libgloss port was merged in 2009, ~14 years seems like plenty
of leeway. Which is to say, no one else can seem to build this
which makes updating & testing things very difficult.
Ignoring that, from what I can tell, this port has only ever built
and installed a crt0.o file. It defines libeval.a & libcygmon.a
targets, but nothing depends on them. The SCRIPTS & BSP variables
are always empty. The original port merge define these in the
configure script as substitutes, but never set the vars, so they
were always replaced with nothing.
I actually broke this build 2 years ago when merging the configure
up a level in commit 30f244155b
("libgloss: merge subdirs that have unique makefile_frags up a
level"). I saw that it was exporting a bunch of vars in the
configure script, but never set them, so I incorrectly assumed
they weren't used. Which means the Makefile has been setting them
to invalid values like literal @bsp_list@ and @script_list@.
Considering no one has complained, I have to assume no one cares
about this port, and we can all stop wasting time on it.