pthread_at_fork: bogus implementation

Because we do not support fork, there is no need to do anything upon fork (and if
it changes in the future, we should revisit this)

So we can get away with this simple implementation that just returns 0.

Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>

libc/pthread.cc

@@ -180,9 +180,25 @@ int pthread_key_create(pthread_key_t* key, void (*dtor)(void*))
     return 0;
 }
 
-extern "C"
-int __pthread_key_create(pthread_key_t* key, void (*dtor)(void*))
-    __attribute__((alias("pthread_key_create")));
+int pthread_atfork(void (*prepare)(void), void (*parent)(void),
+                   void (*child)(void))
+{
+    return 0;
+}
+
+extern "C" int register_atfork(void (*prepare)(void), void (*parent)(void),
+                                void (*child)(void), void *__dso_handle)
+{
+    return 0;
+}
+
+extern "C" {
+    int __register_atfork(void (*prepare)(void), void (*parent)(void),
+                          void (*child)(void), void *__dso_handle) __attribute__((alias("register_atfork")));
+    int __pthread_key_create(pthread_key_t* key, void (*dtor)(void*))
+        __attribute__((alias("pthread_key_create")));
+}
+
 
 int pthread_key_delete(pthread_key_t key)
 {