When installing libbitcoin there are checks of the code, why is this? When installing libbitcoin from here with $ ./install.sh --prefix=/home/me/myprefix --build-boost --disable-shared after most of the compilation is done there seem to be checks of the sourcecode with warnings like thise one: 

In file included from ./include/bitcoin/bitcoin/machine/operation.hpp:159:0,
                 from ./include/bitcoin/bitcoin/chain/script.hpp:31,
                 from ./include/bitcoin/bitcoin/chain/output.hpp:28,
                 from ./include/bitcoin/bitcoin/chain/output_point.hpp:25,
                 from ./include/bitcoin/bitcoin/chain/input.hpp:27,
                 from ./include/bitcoin/bitcoin/chain/transaction.hpp:30,
                 from ./include/bitcoin/bitcoin/chain/block.hpp:31,
                 from ./include/bitcoin/bitcoin.hpp:24,
                 from test/chain/transaction.cpp:20:
./include/bitcoin/bitcoin/impl/machine/operation.ipp:136:15: warning: ‘size_t libbitcoin::machine::variable_uint_size(uint64_t)’ defined but not used [-Wunused-function]
 static size_t variable_uint_size(uint64_t value)
               ^~~~~~~~~~~~~~~~~~


On my Raspberry Pi 2B this goes on for several hours now. Can someone explain why such a huge amount of tests would be usefull?
These are not tests. They are simply warnings generated by the compiler indicating there may be an issue with the code being compiled.

Most likely, it's just being overzealous and the developers are aware of this.