[gtkmm] Doxygen file: Remove deprecated XML_SCHEMA and XML_DTD.

[Murray Cumming <murrayc src gnome org>]

commit 22b4b3b90445a009fa4e004bfaa42b2c907719b6
Author: Murray Cumming <murrayc murrayc com>
Date:   Tue Feb 3 11:38:34 2015 +0100

    Doxygen file: Remove deprecated XML_SCHEMA and XML_DTD.
    
    doxygen has started to warn about these, suggesting that we remove
    them.

 docs/reference/Doxyfile.in |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)
---
diff --git a/docs/reference/Doxyfile.in b/docs/reference/Doxyfile.in
index fb62576..6e129dd 100644
--- a/docs/reference/Doxyfile.in
+++ b/docs/reference/Doxyfile.in
@@ -258,8 +258,6 @@ MAN_LINKS              = NO
 #---------------------------------------------------------------------------
 GENERATE_XML           = NO
 XML_OUTPUT             = xml
-XML_SCHEMA             =
-XML_DTD                =
 XML_PROGRAMLISTING     = NO
 #---------------------------------------------------------------------------
 # configuration options related to the DOCBOOK output