Fix builds without acl, from http://sourceforge.net/p/netatalk/bugs/574/

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>

diff -Nura netatalk-3.1.7.orig/include/atalk/acl.h netatalk-3.1.7/include/atalk/acl.h
--- netatalk-3.1.7.orig/include/atalk/acl.h	2014-12-03 17:34:49.895524464 -0300
+++ netatalk-3.1.7/include/atalk/acl.h	2014-12-03 17:34:58.735243283 -0300
@@ -61,6 +61,7 @@
 #else /* HAVE_ACLS=no */
 
 #define O_NETATALK_ACL 0
+#define O_IGNORE 0
 #define chmod_acl chmod
 
 #endif /* HAVE_ACLS */
