Use timegm() if it is available, so that krb5int_gmt_mktime()
functions correctly on systems configured with a "right"
(leap-second-aware) time zone.  It is arguably an OS bug if a "right"
time zone can be configured on a system that lacks timegm().

Due to a current lack of evidence of affected systems, the additional
workaround of replacing gmtime() with a version that always ignores
leap seconds is deferred.

https://github.com/krb5/krb5/commit/478addb5c6b8b0cdb2454614d5226a23e7b0b356
Commit By: tlyu
Revision: 25018
Changed Files:
U   trunk/src/configure.in
U   trunk/src/util/support/gmt_mktime.c