Use snprintf not sprintf in pg_waldump's timestamptz_to_str.
Use snprintf not sprintf in pg_waldump's timestamptz_to_str.

This could only cause an issue if strftime returned a ridiculously
long timezone name, which seems unlikely; and it wouldn't qualify
as a security problem even then, since pg_waldump (nee pg_xlogdump)
is a debug tool not part of the server.  But gcc 8 has started issuing
warnings about it, so let's use snprintf and be safe.

Backpatch to 9.3 where this code was added.

Discussion: fde6099c36d8933d025d673d98f75d73c4694bff@sss.pgh.pa.us

50wu/gpdb,adam8157/gpdb,adam8157/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,lisakowen/gpdb,lisakowen/gpdb,xinzweb/gpdb,ashwinstar/gpdb,xinzweb/gpdb,50wu/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,50wu/gpdb,greenplum-db/gpdb,lisakowen/gpdb,xinzweb/gpdb,ashwinstar/gpdb,xinzweb/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,jmcatamney/gpdb,lisakowen/gpdb,50wu/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,50wu/gpdb,greenplum-db/gpdb,xinzweb/gpdb,jmcatamney/gpdb,50wu/gpdb,lisakowen/gpdb,50wu/gpdb,ashwinstar/gpdb,adam8157/gpdb,adam8157/gpdb,lisakowen/gpdb,xinzweb/gpdb,adam8157/gpdb,xinzweb/gpdb,xinzweb/gpdb,adam8157/gpdb,ashwinstar/gpdb,adam8157/gpdb,greenplum-db/gpdb,ashwinstar/gpdb,lisakowen/gpdb,greenplum-db/gpdb,50wu/gpdb,lisakowen/gpdb,jmcatamney/gpdb,adam8157/gpdb,jmcatamney/gpdb