attempts to filter off optimize flags when --enable-debug is used

configure.in

@@ -758,6 +758,8 @@ AC_ARG_ENABLE(debug,
     if test "$GCC" = "yes"; then
        CFLAGS="$CFLAGS -W -Wall -Wwrite-strings -pedantic -Wundef -Wpointer-arith -Wcast-align -Wnested-externs"
     fi
+    dnl strip off optimizer flags
+    CFLAGS=`echo $CFLAGS | sed -e 's/-O[0-9 ]//g'`
        ;;
   esac ],
        AC_MSG_RESULT(no)