[pango/pango1-dwrite] PangoWin32: Add private API to clean up IDWriteFontFace

[Chun-wei Fan <fanchunwei src gnome org>]

commit e82edc5c6f4a87e5a92749333edaaf5e24d468a8
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Tue Aug 16 12:54:26 2022 +0800

    PangoWin32: Add private API to clean up IDWriteFontFace
    
    ...which is needed for PangoCairo for Windows, when DirectWrite is used to
    create the cairo_font_face_t, so that that object does get cleaned up when the
    cairo_font_face_t is destroyed.

 pango/pangowin32-dwrite-fontmap.cpp | 9 +++++++++
 pango/pangowin32-private.h          | 3 +++
 2 files changed, 12 insertions(+)
---
diff --git a/pango/pangowin32-dwrite-fontmap.cpp b/pango/pangowin32-dwrite-fontmap.cpp
index 62f2d6362..62d905af8 100644
--- a/pango/pangowin32-dwrite-fontmap.cpp
+++ b/pango/pangowin32-dwrite-fontmap.cpp
@@ -568,3 +568,12 @@ pango_win32_dwrite_font_release (gpointer dwrite_font)
   if (font != NULL)
     font->Release ();
 }
+
+void
+pango_win32_dwrite_font_face_release (gpointer dwrite_font_face)
+{
+  IDWriteFontFace *face = static_cast<IDWriteFontFace *>(dwrite_font_face);
+
+  if (face != NULL)
+    face->Release ();
+}
diff --git a/pango/pangowin32-private.h b/pango/pangowin32-private.h
index 2f9bbf601..1502ecd92 100644
--- a/pango/pangowin32-private.h
+++ b/pango/pangowin32-private.h
@@ -313,6 +313,9 @@ gboolean               pango_win32_dwrite_font_is_monospace   (gpointer
 
 void                   pango_win32_dwrite_font_release        (gpointer               dwrite_font);
 
+_PANGO_EXTERN
+void                   pango_win32_dwrite_font_face_release   (gpointer               dwrite_font_face);
+
 gpointer               pango_win32_logfontw_get_dwrite_font   (LOGFONTW              *logfontw);
 
 PangoFontDescription *