More include optimizations.

diff --git a/debugger/expr.c b/debugger/expr.c
index e45e763..bf5f9c2 100644
--- a/debugger/expr.c
+++ b/debugger/expr.c
@@ -5,6 +5,7 @@
  *
  */
 
+#include "config.h"
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>