sys/windows: add ClientToScreen

core/sys/windows/types.odin

@@ -58,6 +58,7 @@ LPARAM :: LONG_PTR
 WPARAM :: UINT_PTR
 LRESULT :: LONG_PTR
 LPRECT :: ^RECT
+LPPOINT :: ^POINT
 
 UINT8  ::  u8
 UINT16 :: u16

core/sys/windows/user32.odin

@@ -97,6 +97,7 @@ foreign user32 {
 	LoadCursorW :: proc(hInstance: HINSTANCE, lpCursorName: LPCWSTR) -> HCURSOR ---
 
 	GetClientRect :: proc(hWnd: HWND, lpRect: ^RECT) -> BOOL ---
+	ClientToScreen :: proc(hWnd: HWND, lpPoint: LPPOINT) -> BOOL ---
 	SetWindowPos :: proc(
 		hWnd: HWND,
 		hWndInsertAfter: HWND,