gnulib 9e117ae955a5c6a0406140e62b76c3ef50e3bc2b.

* lib/gethrxtime.c, lib/gethrxtime.h, lib/gettime.c, lib/timespec.c,
lib/timespec.h, lib/xtime.h, m4/clock_time.m4, m4/gethrxtime.m4,
m4/gettime.m4, m4/timespec.m4: New files.
* m4/gnulib-cache.m4, m4/gnulib-comp.m4, lib/Makefile.am: Adjust.