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

Change-Id: I0f1f2df817a65f7d5b72c5280451346a0a011d47
diff --git a/lib/decoding/control_channels_decoder_impl.cc b/lib/decoding/control_channels_decoder_impl.cc
index 81ce161..b49582f 100644
--- a/lib/decoding/control_channels_decoder_impl.cc
+++ b/lib/decoding/control_channels_decoder_impl.cc
@@ -70,7 +70,7 @@
     {
       //setup input/output ports
       message_port_register_in(pmt::mp("bursts"));
-      set_msg_handler(pmt::mp("bursts"), boost::bind(&control_channels_decoder_impl::decode, this, _1));
+      set_msg_handler(pmt::mp("bursts"), boost::bind(&control_channels_decoder_impl::decode, this, boost::placeholders::_1));
       message_port_register_out(pmt::mp("msgs"));
     }
 
diff --git a/lib/decoding/tch_f_decoder_impl.cc b/lib/decoding/tch_f_decoder_impl.cc
index 02dc45a..03e8fc8 100644
--- a/lib/decoding/tch_f_decoder_impl.cc
+++ b/lib/decoding/tch_f_decoder_impl.cc
@@ -92,7 +92,7 @@
     {
         //setup input/output ports
         message_port_register_in(pmt::mp("bursts"));
-        set_msg_handler(pmt::mp("bursts"), boost::bind(&tch_f_decoder_impl::decode, this, _1));
+        set_msg_handler(pmt::mp("bursts"), boost::bind(&tch_f_decoder_impl::decode, this, boost::placeholders::_1));
         message_port_register_out(pmt::mp("msgs"));
         message_port_register_out(pmt::mp("voice"));    
 
diff --git a/lib/decoding/tch_h_decoder_impl.cc b/lib/decoding/tch_h_decoder_impl.cc
index b6827f7..f1ba5ba 100644
--- a/lib/decoding/tch_h_decoder_impl.cc
+++ b/lib/decoding/tch_h_decoder_impl.cc
@@ -81,7 +81,7 @@
         {
             //setup input/output ports
             message_port_register_in(pmt::mp("bursts"));
-            set_msg_handler(pmt::mp("bursts"), boost::bind(&tch_h_decoder_impl::decode, this, _1));
+            set_msg_handler(pmt::mp("bursts"), boost::bind(&tch_h_decoder_impl::decode, this, boost::placeholders::_1));
             message_port_register_out(pmt::mp("msgs"));
             message_port_register_out(pmt::mp("voice"));