MINOR: contrib: Make the wireshark peers dissector compile for more distribs.

With a 2.6.8 wireshark, this module could not compile because of ws_version.h
missing header. This patch offers the possibility to compile this plugin without
having to include this header. Furthermore with my wireshark version a
"plugin_release" object is required to make it be loaded by wireshark. This is
a string which seems to have to match a dotted string made of you wireshark
major and minor versions.
diff --git a/contrib/wireshark-dissectors/peers/Makefile b/contrib/wireshark-dissectors/peers/Makefile
index 9e70802..95149e7 100644
--- a/contrib/wireshark-dissectors/peers/Makefile
+++ b/contrib/wireshark-dissectors/peers/Makefile
@@ -1,4 +1,4 @@
-CFLAGS = `pkg-config --cflags wireshark` -g -fPIC
+CFLAGS  = `pkg-config --cflags wireshark` -g -fPIC $(OPTS)
 LDFLAGS = `pkg-config --libs wireshark`
 
 NAME = packet-happp.so