Fix Bug#29155 by enabling file locking on FreeBSD.

It has been disabled because InnoDB has refused to start on
FreeBSD & LinuxThreads, but now it starts just fine.

Approved by:	Heikki

os/os0file.c

@@ -456,10 +456,9 @@ os_file_handle_error_no_exit(
 
 #undef USE_FILE_LOCK
 #define USE_FILE_LOCK
-#if defined(UNIV_HOTBACKUP) || defined(__WIN__) || defined(__FreeBSD__) || defined(__NETWARE__)
+#if defined(UNIV_HOTBACKUP) || defined(__WIN__) || defined(__NETWARE__)
 /* InnoDB Hot Backup does not lock the data files.
  * On Windows, mandatory locking is used.
- * On FreeBSD with LinuxThreads, advisory locking does not work properly.
  */
 # undef USE_FILE_LOCK
 #endif