Set errno to EINVAL if tv.tv_nsec is invalid, and to EPERM if
SetSystemTime fails. Return -1 in case of failure, all for
compatibility with BSD and Linux.
(clock_settime): New function.
* cygwin.din (clock_settime): Export.
* posix.sgml (std-susv4): Add clock_settime.
Move clock_setres from here...
(std-deprec): ... to here.
(std-notes): Correct limitation of clock_setres to only CLOCK_REALTIME.
Add limitation of clock_settime to only CLOCK_REALTIME.
* include/cygwin/version.h (CYGWIN_VERSION_API_MINOR): Bump.