mktime: don’t consult daylight * lib/mktime.c (__mktime_internal): Do not consult __daylight as it has unreliable contents - among other things, the user can set it. It also wasn’t being configured properly for mingw-w64; this problem was reported by Markus Muetzel in <https://lists.gnu.org/r/bug-gnulib/2024-11/msg00126.html>. * m4/mktime.m4 (gl_PREREQ_MKTIME): Do not check for ‘daylight’; no longer needed.