Provide lib/Makefile to enable tags file generation The root Makefile does not hook into lib/ via <bsd.subdir.mk> since it is not a program itself and thus gets included by all others. This means `make tags` skips lib/ and `make -C lib/ tags` does not know what to do; provide a minimal <bsd.lib.mk> stub and hook it up just for the "tags" such that *all* source is browsable via tags. See /usr/share/mk/bsd.README for details. Feedback stsp tb OK tb