RFR/RFA (S): 8231968: getCurrentThreadAllocatedBytes default implementation s/b getThreadAllocatedBytes

[Hohensee, Paul]

Please review this backport to 8u and associated CSR. The backport is clean, but requires a CSR. It’s a follow-on fix (from tip) of the 8u backport of https://bugs.openjdk.java.net/browse/JDK-8231968: [REDO] JDK-8207266 ThreadMXBean::getThreadAllocatedBytes() can be quicker for self thread.

Original JBS issue: https://bugs.openjdk.java.net/browse/JDK-8231968
Original CSR: https://bugs.openjdk.java.net/browse/JDK-8232072
Original patch: https://hg.openjdk.java.net/jdk/jdk/rev/5bb426e9acc4

Backport JBS issue: https://bugs.openjdk.java.net/browse/JDK-8247813
Backport CSR: https://bugs.openjdk.java.net/browse/JDK-8247814
Backport webrev: http://cr.openjdk.java.net/~phh/8231968/webrev.8u.jdk.00/

Thanks,
Paul