Replaced PTR_SEG_TO_LIN macro by exported MapSL function.
Fixed a few ptr/segptr mismatches.
Moved CONV_RECT/POINT macros to wingdi16.h.

diff --git a/windows/win.c b/windows/win.c
index c684504..4500a21 100644
--- a/windows/win.c
+++ b/windows/win.c
@@ -3136,7 +3136,7 @@
 {
  BOOL16		wParam, bResult = 0;
  POINT        pt;
- LPDRAGINFO16	ptrDragInfo = (LPDRAGINFO16) PTR_SEG_TO_LIN(spDragInfo);
+ LPDRAGINFO16	ptrDragInfo = MapSL(spDragInfo);
  WND 	       *ptrQueryWnd = WIN_FindWndPtr(hQueryWnd),*ptrWnd;
  RECT		tempRect;