RFR 8160218: HPack decoder fails when processing header in multiple ByteBuffers

[Pavel Rappo]

Hi,

Could you please review the following change for JDK-8160218?

http://cr.openjdk.java.net/~prappo/8160218/webrev.00/
http://bugs.openjdk.java.net/browse/JDK-8160218

This change addresses two "unrelated" issues that affected decoding of input
data spread across several buffers.

1. An incorrect determining of the final state of string literal decoding in HPACK
2. An incorrect determining of the final buffer in the HttpClient

Thanks,
-Pavel