Test for localtime_r only after including the right MT enabling CFLAGS

Test for localtime_r only after including the right MT enabling CFLAGS

1999-01-11  Sebastian Wilhelmi  <wilhelmi@ira.uka.de>

	* configure.in: Test for localtime_r only after including the
	right MT enabling CFLAGS (i.e. -D_REENTRANT on most systems).

	* gdate.c (g_date_set_time): Emit warning, if no localtime_r
	function is available on thread enabled systems. Define ptm only,
	if really needed, and assert on it.