RFR [10]: 8185362: Replace use of AtomicReferenceFieldUpdater from BufferedInputStream with Unsafe

[Claes Redestad]

Hi,

by using Unsafe.compareAndSetObject instead of AtomicReferenceFieldUpdater
in BufferedInputStream we can avoid some classloading and initialization 
work
during System.initPhase1.

Webrev: http://cr.openjdk.java.net/~redestad/8185362/jdk.00/
Bug: https://bugs.openjdk.java.net/browse/JDK-8185362

/Claes