[COMMITTERS] pgsql: Guard against null t->tm_zone in strftime.c.

Guard against null t->tm_zone in strftime.c.

The upstream IANA code does not guard against null TM_ZONE pointers in this
function, but in our code there is such a check in the other pre-existing
use of t->tm_zone.  We do have some places that set pg_tm.tm_zone to NULL.
I'm not entirely sure it's possible to reach strftime with such a value,
but I'm not sure it isn't either, so be safe.

Per Coverity complaint.

Branch
------
REL9_4_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/e829385f5633c38d8a7baa3de31df537da1fe93a

Modified Files
--------------
src/timezone/strftime.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)