Fix to build with gcc-2.95

OK ajacoutot@

net/avahi/patches/patch-avahi-common_strlst_c

@@ -0,0 +1,21 @@
+$OpenBSD: patch-avahi-common_strlst_c,v 1.1 2011/06/17 15:46:20 sebastia Exp $
+
+fix for gcc-2.95
+
+--- avahi-common/strlst.c.orig	Fri Jun 17 10:06:52 2011
++++ avahi-common/strlst.c	Fri Jun 17 10:07:28 2011
+@@ -31,6 +31,14 @@
+ #include "malloc.h"
+ #include "defs.h"
+ 
++#ifndef va_copy
++#ifdef __va_copy
++#define va_copy(DEST,SRC) __va_copy((DEST),(SRC))
++#else
++#define va_copy(DEST,SRC) memcpy(&(DEST), &(SRC), sizeof(va_list))
++#endif
++#endif
++
+ AvahiStringList*avahi_string_list_add_anonymous(AvahiStringList *l, size_t size) {
+     AvahiStringList *n;
+