Move HDWP to winuser.h.
Convert HWINSTA to STRICT.

diff --git a/dlls/user/misc.c b/dlls/user/misc.c
index 16e72f6..443874b 100644
--- a/dlls/user/misc.c
+++ b/dlls/user/misc.c
@@ -51,10 +51,10 @@
  *    Success: Handle to window station associated with calling process
  *    Failure: NULL
  */
-DWORD WINAPI GetProcessWindowStation(void)
+HWINSTA WINAPI GetProcessWindowStation(void)
 {
     FIXME("(void): stub\n");
-    return 1;
+    return (HWINSTA)1;
 }