[11u] RFR: 8257423: [PPC64] Support -XX:-UseInlineCaches

[Doerr, Martin]

Hi,

I'd like to backport the following PPC64 fixes to 11u together:
https://bugs.openjdk.java.net/browse/JDK-8257423
https://bugs.openjdk.java.net/browse/JDK-8257798
(2nd one is a follow-up fix for some builds)

Both changes don't apply cleanly, but are trivial to resolve:
1st one didn't apply because Universe::narrow_klass_base() was moved to CompressedKlassPointers::base() which is used in old version of MacroAssembler::instr_size_for_decode_klass_not_null.
2nd one didn't apply because of unrelated context changes.
I just had to apply the hunks manually.

Original changes:
https://github.com/openjdk/jdk/commit/1d2d9815
https://github.com/openjdk/jdk/commit/46b35acf

11u backports:
http://cr.openjdk.java.net/~mdoerr/8257423_PPC_UseInlineCaches_11u/webrev.00/
http://cr.openjdk.java.net/~mdoerr/8257798_PPC_build_11u/webrev.00/

Please review.

Best regards,
Martin