psql: Fix exit status when query is canceled

Because of a small thinko in 7844c9918a,
psql -c would exit successfully when a query is canceled.  Fix this so
that it exits with a nonzero status, just like for all other errors.

src/bin/psql/common.c

@@ -1114,7 +1114,7 @@ SendQuery(const char *query)
 			 pset.crosstab_flag || !is_select_command(query))
 	{
 		/* Default fetch-it-all-and-print mode */
-		OK = (ExecQueryAndProcessResults(query, &elapsed_msec, &svpt_gone, false, NULL, NULL) >= 0);
+		OK = (ExecQueryAndProcessResults(query, &elapsed_msec, &svpt_gone, false, NULL, NULL) > 0);
 	}
 	else
 	{