Fix (I hope) for bug [ 673862 ] printing zero length string with postscript does not work

Now descent and externalLeading will be zeroed if the string is empty.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@20835 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/dcpsg.cpp

@@ -1990,6 +1990,8 @@ void wxPostScriptDC::DoGetTextExtent(const wxString& string,
     {
         if (x) (*x) = 0;
         if (y) (*y) = 0;
+        if (descent) (*descent) = 0;
+        if (externalLeading) (*externalLeading) = 0;
         return;
     }