psql: Don't try to print a partition constraint we didn't fetch.

If \d rather than \d+ is used, then verbose is false and we don't ask
the server for the partition constraint; so we shouldn't print it in
that case either.

Maksim Milyutin, per a report from Jesper Pedersen.  Reviewed by
Jesper Pedersen and Amit Langote.

Discussion: http://postgr.es/m/2af5fc4d-7bcc-daa8-4fe6-86274bea363c@redhat.com

src/bin/psql/describe.c

@@ -1985,6 +1985,8 @@ describeOneTableDetails(const char *schemaname,
 							  partdef);
 			printTableAddFooter(&cont, tmpbuf.data);
 
+			if (verbose)
+			{
 				/* If there isn't any constraint, show that explicitly */
 				if (partconstraintdef == NULL || partconstraintdef[0] == '\0')
 					printfPQExpBuffer(&tmpbuf, _("No partition constraint"));
@@ -1992,6 +1994,7 @@ describeOneTableDetails(const char *schemaname,
 					printfPQExpBuffer(&tmpbuf, _("Partition constraint: %s"),
 									  partconstraintdef);
 				printTableAddFooter(&cont, tmpbuf.data);
+			}
 
 			PQclear(result);
 		}