build: disable EthernetFace only with boost 1.56.0, not later versions.

The regression has been fixed in boost version 1.57.0

Change-Id: I187c523b2a715c0fd00ff438840f4275c7c55a64
Refs: #1922
diff --git a/.waf-tools/boost-kqueue.py b/.waf-tools/boost-kqueue.py
index a2ec732..d4d5139 100644
--- a/.waf-tools/boost-kqueue.py
+++ b/.waf-tools/boost-kqueue.py
@@ -8,13 +8,14 @@
 
 BOOST_ASIO_HAS_KQUEUE_CHECK = '''
 #include <boost/asio.hpp>
-#if defined(BOOST_ASIO_HAS_KQUEUE) and BOOST_VERSION >= 105600
-#error "Ethernet face support cannot be enabled on this platform"
+#if defined(BOOST_ASIO_HAS_KQUEUE) and BOOST_VERSION == 105600
+#error "Ethernet face support cannot be enabled on this platform with boost 1.56"
 #endif
 '''
 
 @Configure.conf
 def check_asio_pcap_support(conf):
+    # https://svn.boost.org/trac/boost/ticket/10367
     if conf.check_cxx(msg='Checking if Ethernet face support can be enabled',
                       fragment=BOOST_ASIO_HAS_KQUEUE_CHECK,
                       features='cxx', use='BOOST', mandatory=False):