Check how docopt is used to decide whether generate install target or not. #161
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When I try to use docopt through
FecthContentof cmake, docopt.cpp generate the install target as well, which is annoying.Although there is [a way][stackoverflow-link] to exclude the installation of docopt.cpp, it's not so elegant.
I write this patch by checking how spdlog handling this not-root-project situation. It seems work.