Previously RT_Resolution was returning a hard coded dummy value.
With this change we now use the relevant system call to compute the
clock resolution.

Tested on x86_64-pc-linux-gnu, committed on trunk

2015-01-07  Doug Rupp  <rupp@adacore.com>

	* s-osinte-mingw.ads (LARGE_INTEGR): New subtype.
	(QueryPerformanceFrequency): New imported procedure.
	* s-taprop-mingw.adb (RT_Resolution): Call above and return
	resolution vice a hardcoded value.
	* s-taprop-solaris.adb (RT_Resolution): Call clock_getres and return
	resolution vice a hardcoded value.
	* s-linux-android.ads (clockid_t): New subtype.
	* s-osinte-aix.ads (clock_getres): New imported subprogram.
	* s-osinte-android.ads (clock_getres): Likewise.
	* s-osinte-freebsd.ads (clock_getres): Likewise.
	* s-osinte-solaris-posix.ads (clock_getres): Likewise.
	* s-osinte-darwin.ads (clock_getres): New subprogram.
	* s-osinte-darwin.adb (clock_getres): New subprogram.
	* thread.c (__gnat_clock_get_res) [__APPLE__]: New function.
	* s-taprop-posix.adb (RT_Resolution): Call clock_getres to
	calculate resolution vice hard coded value.