$ brew install tmux
Error: You must `brew link libevent' before tmux can
mdurrant@C02MH2DQFD58:~
$ brew link libevent
Linking /usr/local/Cellar/libevent/2.0.21...
Warning: Could not link libevent. Unlinking...
Error: Permission denied - /usr/local/include/event2

brew install automake

brew install pkg-config
rm configure
sh autogen.sh
./configure
make
make install