Revert the previous change to pthread_once() stub in libc. It is actually

a feature that libstdc++ depends on to simulate the behavior of libc's
internal '__isthreaded' variable.  One benefit of this is that _libc_once()
is now private to _once_stub.c.

Requested by:	kan

lib/libc/gen/_once_stub.c

@@ -33,11 +33,8 @@ __FBSDID("$FreeBSD$");
 #include "un-namespace.h"
 #include "libc_private.h"
 
-/*
- * This implements pthread_once() for the single-threaded case.  It is
- * non-static so that it can be used by _pthread_stubs.c.
- */
-int
+/* This implements pthread_once() for the single-threaded case. */
+static int
 _libc_once(pthread_once_t *once_control, void (*init_routine)(void))
 {
 

lib/libc/gen/_pthread_stubs.c

@@ -105,7 +105,7 @@ pthread_func_entry_t __thr_jtable[PJT_MAX] = {
 	{PJT_DUAL_ENTRY(stub_zero)},    /* PJT_MUTEX_LOCK */
 	{PJT_DUAL_ENTRY(stub_zero)},    /* PJT_MUTEX_TRYLOCK */
 	{PJT_DUAL_ENTRY(stub_zero)},    /* PJT_MUTEX_UNLOCK */
-	{PJT_DUAL_ENTRY(_libc_once)},   /* PJT_ONCE */
+	{PJT_DUAL_ENTRY(stub_zero)},    /* PJT_ONCE */
 	{PJT_DUAL_ENTRY(stub_zero)},    /* PJT_RWLOCK_DESTROY */
 	{PJT_DUAL_ENTRY(stub_zero)},    /* PJT_RWLOCK_INIT */
 	{PJT_DUAL_ENTRY(stub_zero)},    /* PJT_RWLOCK_RDLOCK */

lib/libc/include/libc_private.h

@@ -152,7 +152,6 @@ void _init_tls(void);
  * and multi-threaded applications.
  */
 int _once(pthread_once_t *, void (*)(void));
-int _libc_once(pthread_once_t *, void (*)(void));
 
 /*
  * Set the TLS thread pointer