File icmptunnel-obey-cflags.patch of Package icmptunnel

diff --git a/Makefile b/Makefile
index 5ccc174..135350d 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 CC=gcc
-CFLAGS=-I. -O3 -Wall
+CFLAGS+=-I. -O3 -Wall
 DEPS = icmp.h tunnel.h
 
 %.o: %.c $(DEPS)