[CodeComplete] Remove obsolete isOutputBinary().

Summary:
It's never set to true. Its only effect would be to set stdout to binary mode.
Hopefully we have better ways of doing this by now :-)

Reviewers: hokein

Subscribers: jkorous, arphaman, kadircet, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60871

llvm-svn: 358696