modify the original `no modifications' copyright message, and i've
included his mail into the source file.
The common localization functions between strptime(3) and strftime(3)
have been broken out into timelocal.[ch].
so that all these makefiles can be used to build libc_r too.
Added .if ${LIB} == "c" tests to restrict man page builds to libc
to avoid needlessly building them with libc_r too.
Split libc Makefile into Makefile and Makefile.inc to allow the
libc_r Makefile to include Makefile.inc too.