Mihai Moldovan authored Feb 25, 2017 and Tanu Kaskinen committed Feb 27, 2017

FlatCarbon was the flattened Carbon version used in Mac OS Classic
(i.e., pre Mac OS X.)

It was shipped as legacy software until 10.8, then dropped completely.

Using CoreServices is good enough, manually including FlatCarbon headers
only lead to build failures for users who had old versions of Xcode
lingering around their machines.

v2: don't accidentally drop the OS X semaphore implementation.