- fixed missing stdlib.h and string.h includes everywhere
- removed a couple of unneeded stdlib.h and stdio.h includes

controls/listbox.c

diff --git a/controls/listbox.c b/controls/listbox.c
index 5bc1c71..1c17bef 100644
--- a/controls/listbox.c
+++ b/controls/listbox.c
@@ -5,6 +5,7 @@
  */
 
 #include <string.h>
+#include <stdlib.h>
 #include "wine/winuser16.h"
 #include "winuser.h"
 #include "winerror.h"