Fix typo when converting font to user-readable string

If a font uses both underline and strike-through the user-readable
string would read "underlinedstrikethrough". Prepend a space to the
strike-through translation as is already the case for the other font
adjectives (except the very first one).

Not prepending a space outside of the translation for i18n reasons (such
as RTL though in this case that doesn't apply because of the way the
string gets concatenated).

src/common/fontcmn.cpp

@@ -802,7 +802,7 @@ wxString wxNativeFontInfo::ToUserString() const
 
     if ( GetStrikethrough() )
     {
-        desc << _("strikethrough");
+        desc << _(" strikethrough");
     }
 
     switch ( GetWeight() )