Revert "Sync _emscripten_thread_exit() with musl's pthread_exit"

This reverts commit 5df7db5.

Author: kleisauke

system/lib/pthread/pthread_create.c

@@ -32,8 +32,6 @@
 
 static void dummy_0() {}
 weak_alias(dummy_0, __pthread_tsd_run_dtors);
-weak_alias(dummy_0, __do_orphaned_stdio_locks);
-weak_alias(dummy_0, __dl_thread_cleanup);
 
 static void __run_cleanup_handlers() {
   pthread_t self = __pthread_self();
@@ -315,21 +313,11 @@ void _emscripten_thread_exit(void* result) {
   // Call into the musl function that runs destructors of all thread-specific data.
   __pthread_tsd_run_dtors();
 
-  // If this is the main runtime thread, don't proceed with
-  // termination of the thread, but prepare for exit to call
-  // atexit handlers.
-  if (emscripten_is_main_runtime_thread()) {
-    exit(0);
-  }
-
-  // At this point we are committed to thread termination.
-
-  // The thread list lock must be AS-safe.
   __tl_lock();
 
-  // Process robust list in userspace to handle non-pshared mutexes
-  // and the detached thread case where the robust list head will
-  // be invalid when the kernel would process it.
+  /* Process robust list in userspace to handle non-pshared mutexes
+   * and the detached thread case where the robust list head will
+   * be invalid when the kernel would process it. */
   __vm_lock();
   volatile void *volatile *rp;
   while ((rp=self->robust_list.head) && rp != &self->robust_list.head) {
@@ -346,18 +334,19 @@ void _emscripten_thread_exit(void* result) {
   }
   __vm_unlock();
 
-  __do_orphaned_stdio_locks();
-  __dl_thread_cleanup();
-
-  // Last, unlink thread from the list. This change will not be visible
-  // until the lock is released via __tl_unlock() below.
   if (!--libc.threads_minus_1) libc.need_locks = 0;
+
   self->next->prev = self->prev;
   self->prev->next = self->next;
   self->prev = self->next = self;
 
   __tl_unlock();
 
+  if (emscripten_is_main_runtime_thread()) {
+    exit(0);
+    return;
+  }
+
   // Not hosting a pthread anymore in this worker set __pthread_self to NULL
   __set_thread_state(NULL, 0, 0, 1);
 
@@ -375,10 +364,8 @@ void _emscripten_thread_exit(void* result) {
     // When dynamic linking is enabled we need to keep track of zombie threads
     _emscripten_thread_exit_joinable(self);
 #endif
-
-    // Wake any joiner.
     a_store(&self->detach_state, DT_EXITED);
-    __wake(&self->detach_state, 1, 1);
+    __wake(&self->detach_state, 1, 1); // Wake any joiner.
   }
 }