[COMMITTERS] pgsql: Fix NULL pointer dereference in tuplesort.c.

Fix NULL pointer dereference in tuplesort.c.

Oversight in commit e94568ecc.  This could cause a crash when an external
datum tuplesort of a pass-by-value type required multiple passes.
Per report from Mithun Cy.

Peter Geoghegan

Discussion: https://postgr.es/m/CAD__OujuhfWFULGFSt1fyHqUb8N-XafjJhudwt88V0Qs2o84qg@mail.gmail.com

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/4e46c97fde42fa8ca57d29b9b47f2ebd11ab8105

Modified Files
--------------
src/backend/utils/sort/tuplesort.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)