Change some misleading formatting

Don't put an unrelated compound statement directly below an 'if', which makes
it way too easy to mistake it as the body of the 'if'. No real changes.

src/unix/threadpsx.cpp

@@ -946,7 +946,9 @@ extern "C" void wxPthreadCleanup(void *ptr)
 
 void wxThreadInternal::Cleanup(wxThread *thread)
 {
-    if (pthread_getspecific(gs_keySelf) == 0) return;
+    if (pthread_getspecific(gs_keySelf) == 0)
+        return;
+
     {
         wxCriticalSectionLocker lock(thread->m_critsect);
         if ( thread->m_internal->GetState() == STATE_EXITED )