add --enable-debug for configure

configure.ac

@@ -137,6 +137,23 @@ AC_PATH_PROG(XGETTEXT,xgettext)
 AC_PATH_PROG(HEXDUMP,hexdump)
 PKG_PROG_PKG_CONFIG
 
+# Enable debug 
+AC_ARG_ENABLE([debug],
+    [AS_HELP_STRING([--enable-debug],
+                    [use debug compiler flags and macros (default is no)])],
+    [enable_debug=$enableval],
+    [enable_debug=no])
+
+if test "x$enable_debug" = xyes; then
+    if test "x$GCC" = xyes; then
+        CFLAGS="-g3 -O0 -DDEBUG"
+    fi
+    
+    if test "x$GXX" = xyes; then
+        CXXFLAGS="-g3 -O0 -DDEBUG"
+    fi
+fi 
+
 ## TODO: Remove these hard-coded paths and flags. They are here for the sake of
 ##       compatibility with the legacy buildsystem.
 ##