chinachippatcher: allow additional CFLAGS from the command line.

Fixes building 32bit linux binary on 64bit systems.

Change-Id: Ib58114a979e6aa426370477169a0875a66c9a9c2
diff --git a/rbutil/chinachippatcher/Makefile b/rbutil/chinachippatcher/Makefile
index 390260e..cdce198 100644
--- a/rbutil/chinachippatcher/Makefile
+++ b/rbutil/chinachippatcher/Makefile
@@ -6,7 +6,7 @@
 #                     \/            \/     \/    \/            \/
 # $Id$
 #
-CFLAGS = -g -Wall
+CFLAGS += -g -Wall
 
 OUTPUT = chinachippatcher