Stop read thread of Communication on EOF

Previously the read thread was only stopped if CloseOnEOF was set on the
communication channel. It caused it to spin in case of an EOF because
::select() always reported that we can read from the file descriptor.
This CL change this behavior with stopping the read thread on EOF but do
a disconnect only if CloseOnEOF is enabled.

Differential revision: http://reviews.llvm.org/D9077

llvm-svn: 235291