Bugzilla Bug 291724: removed the workaround for a very old Windows NT 4.0

bug. The workaround modified _tzset related global variables in Microsoft
CRT directly and relied on undocumented properties of the buffers that
_tzname[0] and _tzname[1] point to.  r=darin.
Modified files: ntmisc.c ntthread.c w95thred.c