main-loop: update comment for qemu_mutex_lock/unlock_iothread

Commit 49cf5728 (vl: delay thread initialization after daemonization)
makes the global mutex is taken after daemonization instead before
daemonization by qemu_init_main_loop().
Signed-off-by: NYaowei Bai <baiyaowei@cmss.chinamobile.com>
Message-Id: <1480566640-27264-2-git-send-email-baiyaowei@cmss.chinamobile.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

include/qemu/main-loop.h

@@ -238,7 +238,7 @@ bool qemu_mutex_iothread_locked(void);
  * qemu_mutex_lock_iothread: Lock the main loop mutex.
  *
  * This function locks the main loop mutex.  The mutex is taken by
- * qemu_init_main_loop and always taken except while waiting on
+ * main() in vl.c and always taken except while waiting on
  * external events (such as with select).  The mutex should be taken
  * by threads other than the main loop thread when calling
  * qemu_bh_new(), qemu_set_fd_handler() and basically all other
@@ -253,7 +253,7 @@ void qemu_mutex_lock_iothread(void);
  * qemu_mutex_unlock_iothread: Unlock the main loop mutex.
  *
  * This function unlocks the main loop mutex.  The mutex is taken by
- * qemu_init_main_loop and always taken except while waiting on
+ * main() in vl.c and always taken except while waiting on
  * external events (such as with select).  The mutex should be unlocked
  * as soon as possible by threads other than the main loop thread,
  * because it prevents the main loop from processing callbacks,