Opening and closing the master side of a pseudo terminal without
opening the slave side would result in the pseudo terminal becoming
permanently unavailable. In addition, reopening the slave side
would be possible but not allow for I/O. Finally, attempting to
open an in-use master would wipe its I/O state. These issues have
been resolved.
Change-Id: I9235e3d9aba321803f9280b86b6b5e3646ad5ef3
20173cb5d7