Add std.collect() which will collect multiple HTTP headers into

one single header.

Example usage:

	import std;

	sub vcl_recv {
		std.collect(req.http.foo);
	}
	sub vcl_fetch {
		std.collect(beresp.http.bar);
	}

Fixes: #866

bin/varnishtest/tests/m00006.vtc

+# $Id$
+
+test "test vmod_std.collect()"
+
+server s1 {
+	rxreq
+	expect req.url == "/1"
+	expect req.http.foo == "1, 2"
+	txresp -hdr "bar: a" -hdr "bar: b" -bodylen 1
+
+} -start
+
+varnish v1 -vcl+backend {
+	import std from "${topbuild}/lib/libvmod_std/.libs/libvmod_std.so" ;
+
+	sub vcl_recv {
+		std.collect(req.http.foo);
+	}
+	sub vcl_fetch {
+		std.collect(beresp.http.bar);
+	}
+} -start
+
+client c1 {
+	txreq  -url "/1" -hdr "Foo: 1" -hdr "Foo: 2"
+	rxresp 
+	expect resp.http.bar == "a, b"
+	expect resp.status == 200
+	expect resp.bodylen == 1
+} -run
+
+varnish v1 -badvcl {
+	import std from "${topbuild}/lib/libvmod_std/.libs/libvmod_std.so" ;
+
+	backend b { .host = "127.0.0.1"; }
+
+	sub vcl_recv {
+		std.collect(beresp.http.bar);
+	}
+}

lib/libvmod_std/vmod.vcc

@@ -36,3 +36,4 @@ Function VOID syslog(INT, STRING_LIST)
 Function STRING fileread(PRIV_CALL, STRING)
 Function STRING author(ENUM { phk, des, kristian, mithrandir })
 Function DURATION duration(STRING, DURATION)
+Function VOID collect(HEADER)

lib/libvmod_std/vmod_std.c

@@ -176,3 +176,16 @@ vmod_author(struct sess *sp, const char *id)
 		return ("Tollef");
 	WRONG("Illegal VMOD enum");
 }
+
+void __match_proto__()
+vmod_collect(struct sess *sp, enum gethdr_e e, const char *h)
+{
+	(void)e;
+	(void)sp;
+	(void)h;
+	if (e == HDR_REQ)
+		http_CollectHdr(sp->http, h);
+	else if (e == HDR_BERESP)
+		http_CollectHdr(sp->wrk->beresp, h);
+}
+