Clock_gettime, settime and getres implementations are unncessarily
complex due to using defines and C file inclusion. Simplify the
code by replacing the redundant defines and removing the inclusion,
making it much easier to understand. No functional changes.
* sysdeps/posix/clock_getres.c (__clock_getres): Cleanup.
* sysdeps/unix/clock_gettime.c (__clock_gettime): Cleanup.
* sysdeps/unix/clock_settime.c (__clock_settime): Cleanup.
* sysdeps/unix/sysv/linux/clock_getres.c (__clock_getres): Cleanup.
* sysdeps/unix/sysv/linux/clock_gettime.c (__clock_gettime): Cleanup.
* sysdeps/unix/sysv/linux/clock_settime.c (__clock_settime): Cleanup.