Unused lambda captures in stream-pool/TSP sample

[Insomniac-Ossifrage]

Compiling the sample 'tsp_problem' using Clang 10.0.0 generates the following error:

/home/yago/.local/share/JetBrains/Toolbox/apps/CLion/ch-0/211.6693.114/bin/cmake/linux/bin/cmake --build /home/yago/Desktop/grppi/cmake-build-d-clang --target tsp_problem -- -j 25
[ 50%] Building CXX object samples/stream-pool/TSP/CMakeFiles/tsp_problem.dir/main.cpp.o
/home/yago/Desktop/grppi/samples/stream-pool/TSP/main.cpp:108:7: error: lambda capture 'problem' is not used [-Werror,-Wunused-lambda-capture]
    [&problem, &count, num_cities] (auto )
     ~^~~~~~~~
/home/yago/Desktop/grppi/samples/stream-pool/TSP/main.cpp:108:24: error: lambda capture 'num_cities' is not used [-Werror,-Wunused-lambda-capture]
    [&problem, &count, num_cities] (auto )
                     ~~^~~~~~~~~~
2 errors generated.
make[3]: *** [samples/stream-pool/TSP/CMakeFiles/tsp_problem.dir/build.make:82: samples/stream-pool/TSP/CMakeFiles/tsp_problem.dir/main.cpp.o] Error 1
make[2]: *** [CMakeFiles/Makefile2:1322: samples/stream-pool/TSP/CMakeFiles/tsp_problem.dir/all] Error 2
make[1]: *** [CMakeFiles/Makefile2:1329: samples/stream-pool/TSP/CMakeFiles/tsp_problem.dir/rule] Error 2
make: *** [Makefile:415: tsp_problem] Error 2