RFR (9): 8180498 Remove httpclient internal APIs which supply ByteBuffers to read calls

[Michael McMahon]

Could I get the following change reviewed please?

Bug: https://bugs.openjdk.java.net/browse/JDK-8180498

Webrev: http://cr.openjdk.java.net/~michaelm/8180498/webrev.1/

Thanks,
Michael.