RFR: 8253757: Add LLVM-based backend for hsdis [v2]

[Ludovic Henry]

> When bringing up Hotspot onto new platforms, it is not always possible to compile hsdis because gcc is not yet
> available. For example, for Windows-AArch64 and macOS-AArch64.
> For some such platforms, it is possible to use LLVM as an alternative backend as it also supports a disassembler
> feature.

Ludovic Henry has updated the pull request incrementally with one additional commit since the last revision:

  Merge LLVM backend into hsdis and add Makefile support

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/392/files
  - new: https://git.openjdk.java.net/jdk/pull/392/files/4787a545..9127eb20

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=392&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=392&range=00-01

  Stats: 1881 lines in 7 files changed: 757 ins; 1117 del; 7 mod
  Patch: https://git.openjdk.java.net/jdk/pull/392.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/392/head:pull/392

PR: https://git.openjdk.java.net/jdk/pull/392