pg_upgrade: quote directory names in delete_old_cluster script

This allows the delete script to properly function when special
characters appear in directory paths, e.g. spaces.

Backpatch through 9.0

contrib/pg_upgrade/check.c

@@ -528,7 +528,7 @@ create_script_for_old_cluster_deletion(char **deletion_script_file_name)
 #endif
 
 	/* delete old cluster's default tablespace */
-	fprintf(script, RMDIR_CMD " %s\n", fix_path_separator(old_cluster.pgdata));
+	fprintf(script, RMDIR_CMD " \"%s\"\n", fix_path_separator(old_cluster.pgdata));
 
 	/* delete old cluster's alternate tablespaces */
 	for (tblnum = 0; tblnum < os_info.num_old_tablespaces; tblnum++)
@@ -550,7 +550,7 @@ create_script_for_old_cluster_deletion(char **deletion_script_file_name)
 						PATH_SEPARATOR);
 
 			for (dbnum = 0; dbnum < old_cluster.dbarr.ndbs; dbnum++)
-				fprintf(script, RMDIR_CMD " %s%c%d\n",
+				fprintf(script, RMDIR_CMD " \"%s%c%d\"\n",
 						fix_path_separator(os_info.old_tablespaces[tblnum]),
 						PATH_SEPARATOR, old_cluster.dbarr.dbs[dbnum].db_oid);
 		}
@@ -562,7 +562,7 @@ create_script_for_old_cluster_deletion(char **deletion_script_file_name)
 			 * Simply delete the tablespace directory, which might be ".old"
 			 * or a version-specific subdirectory.
 			 */
-			fprintf(script, RMDIR_CMD " %s%s\n",
+			fprintf(script, RMDIR_CMD " \"%s%s\"\n",
 					fix_path_separator(os_info.old_tablespaces[tblnum]),
 					fix_path_separator(suffix_path));
 			pfree(suffix_path);