Handle underlined and strikethrough attributes in wxGTK native font info.

These attributes were not handled by wxFont::GetNativeFontInfoDesc() as it
only serialized the Pango font description which doesn't support them.

Fix this by handling these attributes explicitly and prepending them to the
Pango font string if necessary.

Closes #14559.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72488 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/fontutil.h

@@ -71,6 +71,11 @@ class WXDLLIMPEXP_CORE wxNativeFontInfo
 public:
 #if wxUSE_PANGO
     PangoFontDescription *description;
+
+    // Pango font description doesn't have these attributes, so we store them
+    // separately and handle them ourselves in {To,From}String() methods.
+    bool m_underlined;
+    bool m_strikethrough;
 #elif defined(_WX_X_FONTLIKE)
     // the members can't be accessed directly as we only parse the
     // xFontName on demand