build: fix memory leaks

Fix the memory leaks found by clang-3.1

Change-Id: Iaae68627ef599c324c9c9ee5737c22e92512862d
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/775
Tested-by: jenkins
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>

src/rtos/rtos.c

@@ -169,6 +169,8 @@ int rtos_qsymbol(struct connection *connection, char *packet, int packet_size)
 			if (target->rtos->symbols[symbol_num].symbol_name == NULL) {
 				LOG_OUTPUT("ERROR: unknown symbol\r\n");
 				gdb_put_packet(connection, "OK", 2);
+				free(hex_name_str);
+				free(name_str);
 				return ERROR_OK;
 			}