Fix receiver termination when using the Osmosdr_Signal_Source implementation for the SignalSource block

docs/changelog.md

@@ -23,6 +23,8 @@ SPDX-FileCopyrightText: 2011-2020 Carles Fernandez-Prades <carles.fernandez@cttc
   parameters for the `DataTypeAdapter`, `InputFilter` and `Resampler` blocks are
   ignored. This was the default behavior in GNSS-SDR v0.0.12, but it changed in
   v0.0.13. This change recovers the old behavior.
+- Fixed the termination of the receiver with `q` + `[Enter]` keys when using the
+  `Osmosdr_Signal_Source` implementation of the `SignalSource` block.
 - Improved General Block diagram, both in content and in image resolution.
 
 &nbsp;

src/core/receiver/gnss_flowgraph.cc

@@ -121,6 +121,7 @@ void GNSSFlowgraph::stop()
             chan->stop_channel();  // stop the acquisition or tracking operation
         }
     top_block_->stop();
+    top_block_->wait();
     running_ = false;
 }