Moved most builtin controls structures into their respective C file.
Created new controls.h file private to user32.dll and moved remaining
builtin controls definitions there.

diff --git a/windows/defdlg.c b/windows/defdlg.c
index 3958570..990a89c 100644
--- a/windows/defdlg.c
+++ b/windows/defdlg.c
@@ -9,7 +9,7 @@
 #include "winbase.h"
 #include "wingdi.h"
 #include "wine/winuser16.h"
-#include "dialog.h"
+#include "controls.h"
 #include "win.h"
 #include "winproc.h"