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

Change-Id: I0f1f2df817a65f7d5b72c5280451346a0a011d47
diff --git a/lib/flow_control/burst_fnr_filter_impl.cc b/lib/flow_control/burst_fnr_filter_impl.cc
index 49ddc4c..ae129ee 100644
--- a/lib/flow_control/burst_fnr_filter_impl.cc
+++ b/lib/flow_control/burst_fnr_filter_impl.cc
@@ -55,7 +55,7 @@
         message_port_register_in(pmt::mp("in"));       
         message_port_register_out(pmt::mp("out"));
 
-        set_msg_handler(pmt::mp("in"), boost::bind(&burst_fnr_filter_impl::process_burst, this, _1));
+        set_msg_handler(pmt::mp("in"), boost::bind(&burst_fnr_filter_impl::process_burst, this, boost::placeholders::_1));
     }
 
     /*
diff --git a/lib/flow_control/burst_sdcch_subslot_filter_impl.cc b/lib/flow_control/burst_sdcch_subslot_filter_impl.cc
index cc72f99..beb3f58 100644
--- a/lib/flow_control/burst_sdcch_subslot_filter_impl.cc
+++ b/lib/flow_control/burst_sdcch_subslot_filter_impl.cc
@@ -54,7 +54,7 @@
         message_port_register_in(pmt::mp("in"));
         message_port_register_out(pmt::mp("out"));
         
-        set_msg_handler(pmt::mp("in"), boost::bind(&burst_sdcch_subslot_filter_impl::process_burst, this, _1));
+        set_msg_handler(pmt::mp("in"), boost::bind(&burst_sdcch_subslot_filter_impl::process_burst, this, boost::placeholders::_1));
     }
 
     /*
diff --git a/lib/flow_control/burst_sdcch_subslot_splitter_impl.cc b/lib/flow_control/burst_sdcch_subslot_splitter_impl.cc
index 267f6b4..ff86296 100644
--- a/lib/flow_control/burst_sdcch_subslot_splitter_impl.cc
+++ b/lib/flow_control/burst_sdcch_subslot_splitter_impl.cc
@@ -63,7 +63,7 @@
             message_port_register_out(pmt::mp("out7"));
         }
         
-        set_msg_handler(pmt::mp("in"), boost::bind(&burst_sdcch_subslot_splitter_impl::process_burst, this, _1));
+        set_msg_handler(pmt::mp("in"), boost::bind(&burst_sdcch_subslot_splitter_impl::process_burst, this, boost::placeholders::_1));
     }
 
     /*
diff --git a/lib/flow_control/burst_timeslot_filter_impl.cc b/lib/flow_control/burst_timeslot_filter_impl.cc
index 4fcd847..e69c60d 100644
--- a/lib/flow_control/burst_timeslot_filter_impl.cc
+++ b/lib/flow_control/burst_timeslot_filter_impl.cc
@@ -54,7 +54,7 @@
         message_port_register_in(pmt::mp("in"));        
         message_port_register_out(pmt::mp("out"));
         
-        set_msg_handler(pmt::mp("in"), boost::bind(&burst_timeslot_filter_impl::process_burst, this, _1));
+        set_msg_handler(pmt::mp("in"), boost::bind(&burst_timeslot_filter_impl::process_burst, this, boost::placeholders::_1));
     }
 
     /*
diff --git a/lib/flow_control/burst_timeslot_splitter_impl.cc b/lib/flow_control/burst_timeslot_splitter_impl.cc
index 1f1572c..d0cea4e 100644
--- a/lib/flow_control/burst_timeslot_splitter_impl.cc
+++ b/lib/flow_control/burst_timeslot_splitter_impl.cc
@@ -60,7 +60,7 @@
         message_port_register_out(pmt::mp("out6"));
         message_port_register_out(pmt::mp("out7"));
         
-        set_msg_handler(pmt::mp("in"), boost::bind(&burst_timeslot_splitter_impl::process_burst, this, _1));
+        set_msg_handler(pmt::mp("in"), boost::bind(&burst_timeslot_splitter_impl::process_burst, this, boost::placeholders::_1));
     }
 
     /*
diff --git a/lib/flow_control/burst_type_filter_impl.cc b/lib/flow_control/burst_type_filter_impl.cc
index c8bbd7e..113a4a6 100644
--- a/lib/flow_control/burst_type_filter_impl.cc
+++ b/lib/flow_control/burst_type_filter_impl.cc
@@ -55,7 +55,7 @@
         message_port_register_in(pmt::mp("bursts_in"));
         message_port_register_out(pmt::mp("bursts_out"));
         
-        set_msg_handler(pmt::mp("bursts_in"), boost::bind(&burst_type_filter_impl::process_burst, this, _1));
+        set_msg_handler(pmt::mp("bursts_in"), boost::bind(&burst_type_filter_impl::process_burst, this, boost::placeholders::_1));
     }
 
     /*
diff --git a/lib/flow_control/dummy_burst_filter_impl.cc b/lib/flow_control/dummy_burst_filter_impl.cc
index 4621187..7e31990 100644
--- a/lib/flow_control/dummy_burst_filter_impl.cc
+++ b/lib/flow_control/dummy_burst_filter_impl.cc
@@ -66,7 +66,7 @@
         message_port_register_in(pmt::mp("in"));        
         message_port_register_out(pmt::mp("out"));
         
-        set_msg_handler(pmt::mp("in"), boost::bind(&dummy_burst_filter_impl::process_burst, this, _1));
+        set_msg_handler(pmt::mp("in"), boost::bind(&dummy_burst_filter_impl::process_burst, this, boost::placeholders::_1));
     }
 
     /*
diff --git a/lib/flow_control/uplink_downlink_splitter_impl.cc b/lib/flow_control/uplink_downlink_splitter_impl.cc
index de5ae30..424d025 100644
--- a/lib/flow_control/uplink_downlink_splitter_impl.cc
+++ b/lib/flow_control/uplink_downlink_splitter_impl.cc
@@ -50,7 +50,7 @@
         message_port_register_in(pmt::mp("in"));
         message_port_register_out(pmt::mp("uplink"));
         message_port_register_out(pmt::mp("downlink"));
-        set_msg_handler(pmt::mp("in"), boost::bind(&uplink_downlink_splitter_impl::process_msg, this, _1));
+        set_msg_handler(pmt::mp("in"), boost::bind(&uplink_downlink_splitter_impl::process_msg, this, boost::placeholders::_1));
     }
 
     void uplink_downlink_splitter_impl::process_msg(pmt::pmt_t msg)