[master] RFR: Load narrowKlass from header, AArch64 assembler implementation

[Roman Kennke]

This implements MacroAssembler::load_klass() to load the (narrow)Klass* from object header. Just like the x86_64 implementation, it checks whether it can take the fast path (object unlocked -> load from upper 32bits of header), or else calls the runtime to get a stable header and load from that.

It adds a runtime call stub, which will also be used in the C2 implementation. It also adds nklass_offset_in_bytes() which will also be used in C2 impl. The part in generate_verify_oop() is a little nasty, I added a comment that explains what's going on.

Testing:
 - [x] tier1 (aarch64)
 - [x] tier2 (aarch64)
 - [x] tier3 (aarch64)

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Commit messages:
 - Add comment
 - Trim code size estimate
 - Merge branch 'master' into load-nklass-interpreter-aarch64
 - Use stub to call load_nklass_runtime()
 - Decode klass in shared path
 - Merge branch 'nklass-runtime' into load-nklass-interpreter-aarch64
 - Fix x86_32
 - x86 parts
 - Load narrowKlass from runtime, decode in generated code
 - Increase code size limit
 - ... and 1 more: https://git.openjdk.java.net/lilliput/compare/8ef4bbda...5b5e79b1

Changes: https://git.openjdk.java.net/lilliput/pull/36/files
 Webrev: https://webrevs.openjdk.java.net/?repo=lilliput&pr=36&range=00
  Stats: 98 lines in 6 files changed: 89 ins; 0 del; 9 mod
  Patch: https://git.openjdk.java.net/lilliput/pull/36.diff
  Fetch: git fetch https://git.openjdk.java.net/lilliput pull/36/head:pull/36

PR: https://git.openjdk.java.net/lilliput/pull/36