RFR: 8320272: Make method_entry_barrier address shared [v3]

[Vladimir Kozlov]

> Currently all platforms have declared their own address variable for method_entry_barrier stub. Some have even slightly different name: nmethod_entry_barrier. For Leyden project one address is preferable.
> In aarch64 code changed `movptr` to `lea` instruction to get relocation info as on x86.
> 
> Tested x86 and aarch64, tier1-4, xcomp, stress.  I need help to test on other platforms. Thanks!

Vladimir Kozlov has updated the pull request incrementally with one additional commit since the last revision:

  Addition RISC-V patch

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/16708/files
  - new: https://git.openjdk.org/jdk/pull/16708/files/3af07981..bbf946c6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16708&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16708&range=01-02

  Stats: 16 lines in 2 files changed: 10 ins; 3 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/16708.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16708/head:pull/16708

PR: https://git.openjdk.org/jdk/pull/16708