* libc/time/month_lengths.c: New file with __month_lengths array
(previously mon_lengths array in mktm_r.c)
* libc/time/tzcalc_limits.c: New file with __tzcalc_limits() from
mktm_r.c
* libc/time/lcltime_r.c (localtime_r): Simplify by changing call to
_mktm_r() with call to gmtime_r() and code moved from _mktm_r() which
was used to do time zone adjustments
* libc/time/gmtime_r.c (gmtime_r): Simplify by moving all relevant
code from _mktm_r(), breaking all dependencies on time zone related
functions
* libc/time/mktm_r.c: Delete file
* libc/time/local.h: Update accordingly - remove declaration of
_mktm_r(), add declaration of __month_lengths[]
* libc/time/Makefile.am: Modify accordingly.
* libc/time/Makefile.in: Regenerate.