Makefile.PL: drop generated lib/PublicInbox.pm in blib/
Running "make test" on this project doesn't pass unless you've got an
existing PublicInbox.pm in your @INC, presumably nobody's set this up
on a fresh machine in a while.
This Makefile.PL trickery seems to do it, I've validated this with
this ad-hoc test of committing blib/ and Makefile to the repository:
git clean -dxf; perl Makefile.PL && make -j8 all && git add -f blib Makefile.PL Makefile && git commit -m"now"
Running that in interactive rebase before/after shows that only the
PublicInbox.pm file was added to blib/lib/. We use $(INST_LIB) instead
of a hardcoded 'blib/lib' now, but it's what ExtUtils::MakeMaker
recommends, so it's probably for the better.
As far as I can tell this broke with
1fae720d (build: generate
PublicInbox.pm with $VERSION, 2021-04-01), but I have not tested
that. See also
1fae720d (build: generate PublicInbox.pm with $VERSION,
2021-04-01) which made the PublicInbox.pm a generated file.