Change pthread_cleanup_{push,pop} to macros that store the cleanup info

on the stack instead of mallocing the list and move the APIs from libpthread
to libc so that they can be used inside libc.
Note: the standard was explicitly written to permit/support this
"macro with unmatched brace" style and it's what basically everyone
else already does.  We xor the info with random cookies with a
random magic to detect/trip-up overwrites.
Major bump to both libc and libpthread due to the API move.
ok mpi@

src/include/pthread.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: pthread.h,v 1.1 2017/10/15 23:40:33 guenther Exp $	*/
+/*	$OpenBSD: pthread.h,v 1.2 2017/10/28 21:23:14 guenther Exp $	*/
 
 /*
  * Copyright (c) 1993, 1994 by Chris Provenzano, proven@mit.edu
@@ -179,10 +179,41 @@ enum pthread_mutextype {
 #define PTHREAD_MUTEX_STRICT_NP		PTHREAD_MUTEX_STRICT_NP
 #define PTHREAD_MUTEX_DEFAULT		PTHREAD_MUTEX_STRICT_NP
 
+/*
+ * On-stack structure for the pthread_cleanup_{push,pop} macros
+ * The actual values are xor'ed with random cookies.
+ */
+struct __thread_cleanup {
+	__uintptr_t __tc_magic;
+	__uintptr_t __tc_next;
+	__uintptr_t __tc_fn;
+	__uintptr_t __tc_arg;
+};
+
+/*
+ * These macro must be used in pairs in the same scope, such that
+ * pthread_cleanup_push() can start a block declaring a variable and
+ * pthread_cleanup_pop() closes that same block.  Any other usage
+ * violates the requirements of the POSIX and Single UNIX standards.
+ */
+#define	pthread_cleanup_push(cb, arg)					\
+	{	/* MATCHED BY CLOSE BRACKET IN pthread_cleanup_pop() */	\
+		struct __thread_cleanup __tc;				\
+		_thread_cleanup_push(cb, arg, &__tc);
+
+#define	pthread_cleanup_pop(execute)					\
+		_thread_cleanup_pop(execute, &__tc);			\
+	}	/* MATCHED BY OPEN BRACKET IN pthread_cleanup_push() */
+
+
+
 /*
  * Thread function prototype definitions:
  */
 __BEGIN_DECLS
+void		_thread_cleanup_pop(int _execute, struct __thread_cleanup *_tc);
+void		_thread_cleanup_push(void (*_fn)(void *), void *_arg,
+		    struct __thread_cleanup *_tc);
 int		pthread_atfork(void (*)(void), void (*)(void), void (*)(void));
 int		pthread_attr_destroy(pthread_attr_t *);
 int		pthread_attr_getstack(const pthread_attr_t *,
@@ -197,8 +228,6 @@ int		pthread_attr_setstack(pthread_attr_t *, void *, size_t);
 int		pthread_attr_setstackaddr(pthread_attr_t *, void *);
 int		pthread_attr_setguardsize(pthread_attr_t *, size_t);
 int		pthread_attr_setdetachstate(pthread_attr_t *, int);
-void		pthread_cleanup_pop(int);
-void		pthread_cleanup_push(void (*) (void *), void *routine_arg);
 int		pthread_condattr_destroy(pthread_condattr_t *);
 int		pthread_condattr_init(pthread_condattr_t *);