pgsql: This routine was calling ecpg_alloc to allocate to memory but di

This routine was calling ecpg_alloc to allocate to memory but did not
actually check the returned pointer allocated, potentially NULL which
could be the result of a malloc call.

Issue noted by Coverity, fixed by Michael Paquier <michael@otacoo.com>

Branch
------
REL9_0_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/d4215954747e5463ea5c161aa776040ec45c40e4

Modified Files
--------------
src/interfaces/ecpg/ecpglib/descriptor.c |    6 ++----
src/interfaces/ecpg/ecpglib/execute.c    |    6 ++----
src/interfaces/ecpg/ecpglib/extern.h     |    4 ++--
src/interfaces/ecpg/ecpglib/memory.c     |   22 +++++++++++++++++++++-
4 files changed, 27 insertions(+), 11 deletions(-)