Fix compilation error: '_1' was not declared in this scope

Change-Id: I0f1f2df817a65f7d5b72c5280451346a0a011d47
diff --git a/lib/misc_utils/extract_cmc_impl.cc b/lib/misc_utils/extract_cmc_impl.cc
index 04b0afc..c313b58 100644
--- a/lib/misc_utils/extract_cmc_impl.cc
+++ b/lib/misc_utils/extract_cmc_impl.cc
@@ -83,7 +83,7 @@
               gr::io_signature::make(0, 0, 0))
     {
         message_port_register_in(pmt::mp("msgs"));
-        set_msg_handler(pmt::mp("msgs"), boost::bind(&extract_cmc_impl::process_messages, this, _1));
+        set_msg_handler(pmt::mp("msgs"), boost::bind(&extract_cmc_impl::process_messages, this, boost::placeholders::_1));
     }
     
     /*