Don't check for LVS_EX_LABELTIP being defined, it always is

This constant is defined in wx/msw/missing.h if it's not defined, so testing
for whether it's defined here doesn't make sense -- and the comment about not
using it under Windows CE which is not supported any more anyhow doesn't make
sense neither.

src/msw/listctrl.cpp

@@ -294,11 +294,7 @@ void wxListCtrl::MSWSetExListStyles()
     ::SendMessage
     (
         GetHwnd(), LVM_SETEXTENDEDLISTVIEWSTYLE, 0,
-        // LVS_EX_LABELTIP shouldn't be used under Windows CE where it's
-        // not defined in the SDK headers
-#ifdef LVS_EX_LABELTIP
         LVS_EX_LABELTIP |
-#endif
         LVS_EX_FULLROWSELECT |
         LVS_EX_SUBITEMIMAGES |
         LVS_EX_DOUBLEBUFFER |