pgsql: Suppress -Warray-bounds warning in 9.2's xlog.c.

Suppress -Warray-bounds warning in 9.2's xlog.c.

Late-model gcc delivers a confusing warning "'memcpy' offset [0, 63]
is out of the bounds [0, 0]" here, which turns out to be because it
thinks the "record" pointer might be NULL, which again is because
it doesn't know ereport(PANIC) won't return. The least invasive
way to fix that is to insert a couple of abort() calls. It's
surprising/fortunate that we don't have this issue in more places
... but this is the last remaining build warning with gcc 11.2.1,
so I'll settle for a narrow fix.

Discussion: https://postgr.es/m/d0316012-ece7-7b7e-2d36-9c38cb77cb3b@enterprisedb.com

Branch
------
REL9_2_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/985c8de212faa5a4c983005d4192fb7e543cf5ab

Modified Files
--------------
src/backend/access/transam/xlog.c | 4 ++++
1 file changed, 4 insertions(+)