pgsql: Don't use the result of strcmp as if it were a boolean.

Log Message:
-----------
Don't use the result of strcmp as if it were a boolean.
A service of your local coding style police.

Modified Files:
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pgsql/src/backend/commands:
dbcommands.c (r1.221 -> r1.222)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/dbcommands.c?r1=1.221&r2=1.222)