Remove CXXFLAGS override

--- a/configure.ac
+++ b/configure.ac
@@ -62,12 +62,12 @@ AC_ARG_ENABLE(deprecated, [  --disable-deprecated  Disable deprecated GTK functi
 AC_ARG_ENABLE([debug],
               [AS_HELP_STRING([--enable-debug], [Enable debugging (default is yes)])],
               [case "${enable_debug}" in
-                 yes) CXXFLAGS="$CXXFLAGS -g -O0"
+                 yes)
                       AC_DEFINE([DEBUG], [1], [Enable DEBUG code])
                       ;;
-                 no) CXXFLAGS="$CXXFLAGS -O2";;
+                 no) ;;
                  *) AC_MSG_ERROR([bad value ${enable_debug} for --enable-debug]) ;;
-               esac], CXXFLAGS="$CXXFLAGS -O2")
+               esac], [])
 
 
 AC_CONFIG_FILES([Makefile
--- a/configure.ac
+++ b/configure.ac
@@ -9,8 +9,6 @@ AM_INIT_AUTOMAKE([foreign])
 AC_CONFIG_HEADERS([config.h])
 
 # DON'T REMOVE - Fix the flags defaults
-# ${CFLAGS=""}
-${CXXFLAGS=""}
 
 # Checks for programs.
 AC_PROG_CC