pgsql: Fix a memory leak in psql: we'd leak a few PGresult handles if a

Log Message:
-----------
Fix a memory leak in psql: we'd leak a few PGresult handles if
a connectivity error occurred while executing one of the queries
for "\d <table>". Not serious, but still worth fixing. Patch from
Brendan Jurd.

Modified Files:
--------------
pgsql/src/bin/psql:
describe.c (r1.147 -> r1.148)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/describe.c.diff?r1=1.147&r2=1.148)