Add includes (make cpplint's build/include_what_you_use filter happy)

src/algorithms/signal_source/gnuradio_blocks/fifo_reader.h

@@ -21,6 +21,7 @@
 #include "gnss_block_interface.h"
 #include <gnuradio/sync_block.h>
 #include <fstream>  // std::ifstream
+#include <string>
 
 /** \addtogroup Signal_Source
  * \{ */

src/algorithms/signal_source/gnuradio_blocks/labsat23_source.cc

@@ -28,6 +28,7 @@
 #include <bitset>
 #include <exception>
 #include <iostream>
+#include <memory>
 #include <sstream>
 #include <utility>
 

src/algorithms/signal_source/gnuradio_blocks/unpack_byte_4bit_samples.h

@@ -21,6 +21,7 @@
 #define GNSS_SDR_UNPACK_BYTE_4BIT_SAMPLES_H
 
 #include <gnuradio/sync_interpolator.h>
+#include <memory>
 
 /** \addtogroup Signal_Source
  * \{ */