Don't take trailing whitespace into account when ellipsizing

Trailing spaces and tabs are invisible, so the string shouldn't be
truncated (possibly losing some printable characters that could have
been displayed) just in order to show "..." instead of them.

src/common/ctrlcmn.cpp

@@ -596,6 +596,7 @@ wxString wxControlBase::Ellipsize(const wxString& label, const wxDC& dc,
     {
         if ( pc == label.end() || *pc == wxS('\n') )
         {
+            curLine.Trim();
             curLine = DoEllipsizeSingleLine(curLine, dc, mode, maxFinalWidth,
                                             replacementWidth, flags);