cobol: Eliminate unguarded clock_gettime dependencies. [PR119975]

These changes are help make it possible to compile on MacOS.  In
addition to guarding clock_settime() calls, it removes the use
of structures and constants needed for clock_settime().

libgcobol/ChangeLog:

	PR cobol/119975
	* intrinsic.cc (__gg__current_date): Eliminate CLOCK_REALTIME.
	(__gg__seconds_past_midnight): Likewise.
	(__gg__formatted_current_date): Likewise.
	(__gg__random): Likewise.
	(__gg__random_next): Likewise.
	* libgcobol.cc: include <sys/time.h>.
	(__gg__abort): Eliminate CLOCK_REALTIME.
	(cobol_time): Likewise.
	(get_time_nanoseconds): Rename.
	(get_time_nanoseconds_local): Comment; Eliminate CLOCK_REALTIME.
	(__gg__clock_gettime): Likewise.
	(__gg__get_date_hhmmssff): Likewise.
	* libgcobol.h (__gg__clock_gettime): Eliminate clockid_t from declaration.

(cherry picked from commit 582dda08eabc8f7dc9c504c0010d778bd6ff09b2)