Allow building on platforms without `struct tm.tm_gmtoff`, `timezone`, `daylight`
I'm not happy about this because the results are non-intuitive, but that
looks like something which originates in libyang's attempts to use local
TZ everywhere instead of normalizing to UTC time.
But hey, this only matters on a platform which cannot "easily" represent
timezones in `struct tm`, or for which we cannot determine the TZ/DST
status without going the extra mile of writing non-POSIX stuff. So as
long as we mark the returned value with "I cannot really vouch for the
TZ", this *might* even be standard-compliant.
diff --git a/compat/compat.h.in b/compat/compat.h.in
index 9383f2d..8ff7c89 100644
--- a/compat/compat.h.in
+++ b/compat/compat.h.in
@@ -58,6 +58,8 @@
#cmakedefine HAVE_STRCHRNUL
#cmakedefine HAVE_GET_CURRENT_DIR_NAME
#cmakedefine HAVE_PTHREAD_MUTEX_TIMEDLOCK
+#cmakedefine HAVE_TM_GMTOFF
+#cmakedefine HAVE_TIME_H_TIMEZONE
#ifndef bswap64
#define bswap64(val) \