[libxmlplusplus] Doxyfile.in: Remove obsolete glibmm configuration constants

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 75bdd19f6c0b217e8f7a6fc5c32c889941b1903b
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Thu Mar 21 16:24:15 2019 +0100

    Doxyfile.in: Remove obsolete glibmm configuration constants
    
    They have been removed from glibmm. See issue glibmm#22.

 docs/reference/Doxyfile.in | 4 ----
 1 file changed, 4 deletions(-)
---
diff --git a/docs/reference/Doxyfile.in b/docs/reference/Doxyfile.in
index bd29117..c00c367 100644
--- a/docs/reference/Doxyfile.in
+++ b/docs/reference/Doxyfile.in
@@ -293,10 +293,6 @@ PREDEFINED             = __cplusplus \
                          "G_GNUC_PURE=" \
                          "G_GNUC_WARN_UNUSED_RESULT=" \
                          "G_MODULE_EXPORT=" \
-                         GLIBMM_DEFAULT_SIGNAL_HANDLERS_ENABLED \
-                         GLIBMM_EXCEPTIONS_ENABLED \
-                         GLIBMM_PROPERTIES_ENABLED \
-                         GLIBMM_VFUNCS_ENABLED \
                          "LIBXMLXX_API="
 EXPAND_AS_DEFINED      = LIBXMLXX_MAJOR_VERSION \
                          LIBXMLXX_MINOR_VERSION \