[libunwind] Add initial ARM64EC support (#138583)

ARM64EC defines `__x86_64__`, which is sufficient to make most C/C++
code behave correctly. To preserve an external ABI compatible with
x86_64, this patch uses the x86_64 context layout and implements
`unw_getcontext` by storing the appropriate aarch64 registers according
to the mapping defined by the ARM64EC ABI.

GitOrigin-RevId: 84c1564d1825880d463d9f85153812f1f6805289
2 files changed
tree: 095e62c242af0181cd374e55e00a56e64437ab2c
  1. cmake/
  2. docs/
  3. include/
  4. src/
  5. test/
  6. .clang-format
  7. CMakeLists.txt
  8. LICENSE.TXT