[newlib-cygwin] Cygwin: pthread: Fix handle leak in pthread_once.

[Takashi Yano]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=2c5433e5da8216aaf7458e50c63683c68fb0d3e8

commit 2c5433e5da8216aaf7458e50c63683c68fb0d3e8
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Wed Jan 24 22:33:12 2024 +0900

    Cygwin: pthread: Fix handle leak in pthread_once.
    
    If pthread_once() is called with pthread_once_t initialized using
    PTREAD_ONCE_INIT, pthread_once does not release pthread_mutex used
    internally. This patch fixes that by calling pthread_mutex_destroy()
    in the thread which has called init_routine.
    
    Reviewed-by: Corinna Vinschen <corinna@vinschen.de>
    Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>

Diff:
---
 winsup/cygwin/thread.cc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/winsup/cygwin/thread.cc b/winsup/cygwin/thread.cc
index 7bb4f9fc8..0f8327831 100644
--- a/winsup/cygwin/thread.cc
+++ b/winsup/cygwin/thread.cc
@@ -2060,6 +2060,9 @@ pthread::once (pthread_once_t *once_control, void (*init_routine) (void))
     {
       init_routine ();
       once_control->state = 1;
+      pthread_mutex_unlock (&once_control->mutex);
+      while (pthread_mutex_destroy (&once_control->mutex) == EBUSY);
+      return 0;
     }
   /* Here we must remove our cancellation handler */
   pthread_mutex_unlock (&once_control->mutex);