[gtkmm] Add -Wformat-security to the --enable-warnings=fatal build.

[Murray Cumming <murrayc src gnome org>]

commit 6e2270b72d6f7def5ab9426e95bfc361be417fc5
Author: Murray Cumming <murrayc murrayc com>
Date:   Wed Jun 29 09:38:39 2011 +0200

    Add -Wformat-security to the --enable-warnings=fatal build.
    
    * configure.ac: This seems to be popular now.

 ChangeLog    |    6 ++++++
 configure.ac |    2 +-
 2 files changed, 7 insertions(+), 1 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 78004be..db1a602 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2011-06-29  Murray Cumming  <murrayc murrayc com>
 
+	Add -Wformat-security to the --enable-warnings=fatal build.
+
+	* configure.ac: This seems to be popular now.
+
+2011-06-29  Murray Cumming  <murrayc murrayc com>
+
 	ComboBoxText: Constructor: Set entry-text-column and d-column.
 
 	* gtk/src/comboboxtext.ccg: gtk_combo_box_text_new() does this, 
diff --git a/configure.ac b/configure.ac
index c94947f..456574d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -99,7 +99,7 @@ AC_CHECK_FUNCS([flockfile funlockfile getc_unlocked mkfifo])
 # Evaluate the --enable-warnings=level option.
 MM_ARG_ENABLE_WARNINGS([GTKMM_WXXFLAGS],
                        [-Wall],
-                       [-pedantic -Wall -Wextra  -Wno-long-long -DGSEAL_ENABLE],
+                       [-pedantic -Wall -Wextra -Wformat-security -Wno-long-long -DGSEAL_ENABLE],
                        [G PANGO ATK GDK GDK_PIXBUF GTK GLIBMM ATKMM PANGOMM CAIROMM])
 
 AC_CONFIG_FILES([Makefile