Bug 519886 - eclipse CDT failed to create PTY on macOS 10.13 beta

Fixed by getting rid of legacy code for opening a master pty, and
copying the related code from org.eclipse.cdt.core.linux instead.
Only getpt() had to be replaced by posix_openpt(). Compiled on
OSX 10.12 - tested on MacOSX 10.8 and 10.13 beta 7 (64-bit each).

Change-Id: Idade001aed41abafc0d500695a4b51179bb9b738
Signed-off-by: Martin Oberhuber <mober.at+eclipse@gmail.com>
(cherry picked from commit a0ab38124c6e78eeacedf92feb685f7e4d3002d0)
5 files changed