Cygwin: debugging: convert muto to SRWLOCK

this avoids having to call debug_init, because the SRWLOCK
is statically initialized.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/dcrt0.cc

@@ -854,10 +854,6 @@ dll_crt0_1 (void *)
   strace.microseconds ();
 #endif
 
-  /* Initialize debug muto, if DLL is built with --enable-debugging.
-     Need to do this before any helper threads start. */
-  debug_init ();
-
   cygbench ("pre-forkee");
   if (in_forkee)
     {

winsup/cygwin/debug.cc

@@ -22,30 +22,16 @@ details. */
 
 class lock_debug
 {
-  static muto locker;
+  static NO_COPY SRWLOCK lock;
  public:
-  lock_debug ()
-  {
-    locker.acquire (INFINITE);
-  }
-  void unlock ()
-  {
-    locker.release ();
-  }
-  ~lock_debug () {unlock ();}
-  friend void debug_init ();
+  lock_debug () { AcquireSRWLockExclusive (&lock); }
+  ~lock_debug () { ReleaseSRWLockExclusive (&lock); }
 };
 
-muto NO_COPY lock_debug::locker;
+SRWLOCK NO_COPY lock_debug::lock = SRWLOCK_INIT;
 
 static bool mark_closed (const char *, int, HANDLE, const char *, bool);
 
-void
-debug_init ()
-{
-  lock_debug::locker.init ("debug_lock");
-}
-
 /* Find a registered handle in the linked list of handles. */
 static handle_list *
 find_handle (HANDLE h)
@@ -138,7 +124,6 @@ add_handle (const char *func, int ln, HANDLE h, const char *name, bool inh)
 
   if ((hl = newh ()) == NULL)
     {
-      here.unlock ();
       debug_printf ("couldn't allocate memory for %s(%d): %s(%p)",
 		    func, ln, name, h);
       return;