Improve includes with the aid of include-what-you-use (IWYU)

See rationale at https://github.com/include-what-you-use/include-what-you-use/blob/master/docs/WhyIWYU.md

src/algorithms/signal_source/libs/gnss_sdr_valve.cc

@@ -32,11 +32,12 @@
  */
 
 #include "gnss_sdr_valve.h"
-#include "control_message_factory.h"
-#include <glog/logging.h>
-#include <gnuradio/io_signature.h>
-#include <algorithm>  // for min
-#include <cstring>    // for memcpy
+#include "control_message_factory.h"  // for ControlMessageFactory
+#include <glog/logging.h>             // for LOG
+#include <gnuradio/io_signature.h>    // for io_signature
+#include <algorithm>                  // for min
+#include <cstring>                    // for memcpy
+#include <unistd.h>                   // for usleep
 #include <utility>
 
 Gnss_Sdr_Valve::Gnss_Sdr_Valve(size_t sizeof_stream_item,

src/algorithms/signal_source/libs/gnss_sdr_valve.h

@@ -35,8 +35,10 @@
 #define GNSS_SDR_GNSS_SDR_VALVE_H_
 
 #include <boost/shared_ptr.hpp>
-#include <gnuradio/msg_queue.h>
-#include <gnuradio/sync_block.h>
+#include <gnuradio/msg_queue.h>   // for msg_queue, msg_queue::sptr
+#include <gnuradio/sync_block.h>  // for sync_block
+#include <gnuradio/types.h>       // for gr_vector_const_void_star
+#include <cstddef>                // for size_t
 #include <cstdint>
 
 boost::shared_ptr<gr::block> gnss_sdr_make_valve(size_t sizeof_stream_item,

src/algorithms/signal_source/libs/rtl_tcp_commands.cc

@@ -31,7 +31,9 @@
  */
 
 #include "rtl_tcp_commands.h"
-#include <string>
+#include <boost/asio/buffer.hpp>                  // for buffer
+#include <boost/asio/detail/impl/socket_ops.ipp>  // for host_to_network_long
+#include <cstring>                                // for memcpy
 
 boost::system::error_code rtl_tcp_command(RTL_TCP_COMMAND id, unsigned param, boost::asio::ip::tcp::socket &socket)
 {

src/algorithms/signal_source/libs/rtl_tcp_commands.h

@@ -32,7 +32,8 @@
 #ifndef GNSS_SDR_RTL_TCP_COMMANDS_H
 #define GNSS_SDR_RTL_TCP_COMMANDS_H
 
-#include <boost/asio/ip/tcp.hpp>
+#include <boost/asio/ip/tcp.hpp>        // for tcp, tcp::socket
+#include <boost/system/error_code.hpp>  // for error_code
 
 /// Command IDs for configuration rtl_tcp
 enum RTL_TCP_COMMAND