Avoid potential UCollator leak for older ICU versions.

ICU versions 53 and earlier rely on icu_set_collation_attributes() to
process the attributes in the locale string. Avoid leaking the
already-opened UCollator object if an error is encountered.

Discussion: https://postgr.es/m/04182066-7655-344a-b8b7-040b1b2490fb%40enterprisedb.com
Reviewed-by: Peter Eisentraut

src/backend/utils/adt/pg_locale.c

@@ -2810,9 +2810,12 @@ icu_set_collation_attributes(UCollator *collator, const char *loc)
 			 * message across ICU versions.
 			 */
 			if (U_FAILURE(status))
+			{
+				ucol_close(collator);
 				ereport(ERROR,
 						(errmsg("could not open collator for locale \"%s\": %s",
 								loc, u_errorName(status))));
+			}
 		}
 	}