include: Add EnableMouseInPointer() declaration.

include/winuser.h

@@ -3576,6 +3576,7 @@ WINUSERAPI INT         WINAPI DrawTextExW(HDC,LPWSTR,INT,LPRECT,UINT,LPDRAWTEXTP
 #define                       DrawTextEx WINELIB_NAME_AW(DrawTextEx)
 WINUSERAPI BOOL        WINAPI EmptyClipboard(void);
 WINUSERAPI BOOL        WINAPI EnableMenuItem(HMENU,UINT,UINT);
+WINUSERAPI BOOL        WINAPI EnableMouseInPointer(BOOL);
 WINUSERAPI BOOL        WINAPI EnableScrollBar(HWND,UINT,UINT);
 WINUSERAPI BOOL        WINAPI EnableWindow(HWND,BOOL);
 WINUSERAPI BOOL        WINAPI EndDeferWindowPos(HDWP);