This type of error ( 'libraries/fc'):
git submodule update --init --recursive
fatal: reference is not a tree: 31adee49d91275cc63aa3a47b3a9e3c826baccca
Unable to checkout '31adee49d91275cc63aa3a47b3a9e3c826baccca' in submodule path 'libraries/fc'
can be bypassed by the following code:
cd libraries/fc
git checkout master
git pull
git submodule update --init --recursive
cd ../..
cmake -D CMAKE_BUILD_TYPE=Release .
make witness_node cli_wallet