[Ada] Set GNAT.OS_Lib.GM_Split's granularity back to 1 second

[Ada] Set GNAT.OS_Lib.GM_Split's granularity back to 1 second

The modification to round time up to even second was added decades ago.
It was done to avoid unneeded recompilations when the project was built
on non-FAT filesystems and then moved to FAT filesystems. Such a
situation is now very rare and does not deserve time distortion.

2019-08-20  Dmitriy Anisimkov  <anisimko@adacore.com>

gcc/ada/

	* adaint.c (__gnat_to_gm_time): On _WIN32, don't round time up
	to even second.

From-SVN: r274736