Remove java.nio.channels.* classes without test coverage.

Removed classes come from openJdk 1.7 and were never
implemented before. We lack a testing suite to verify that
they are working correctly. Those clasess might by
re-added in further releases

Bug: 27117463
Change-Id: Ia7554a9182507b9fa1c1b6db9573ab68cb641f36
(cherry picked from commit 5fbc42d6)