Project file cleanup: removed references to the pthreads-based buffered channel implementation.
Project file cleanup: removed references to the pthreads-based buffered channel implementation.

They don't support select(), and won't without much unnecessary pain.
(Converting the SChanSemaphore to pthreads-mutexes under the hood would be much easier and would probably perform better anyway.)

glessard/swift-channels,glessard/swift-channels