Don't leave too much blank space in wxDatePickerCtrl under XP.

In our efforts to account for the longest possible string we made the control
too wide by default which didn't look very good, so reduce the amount of space
added to it, this still seems to be (just) enough for all the reasonable date
formats (tested under Windows XP SP3 with default DPI).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78417 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/datetimectrl.cpp

@@ -136,7 +136,7 @@ wxSize wxDateTimePickerCtrl::DoGetBestSize() const
         // representation of the current value because the control must accommodate
         // any date and while the widths of all digits are usually about the same,
         // the width of the month string varies a lot, so try to account for it
-        s += wxT("WW");
+        s += wxS("W");
 
         size = dc.GetTextExtent(s);