unwind: rename `__personality_routine` to `_Unwind_Personality_Fn`

This patch renames `__personality_routine` to `_Unwind_Personality_Fn`
in `unwind.h`. Both `unwind.h` from clang and GCC headers use this name
instead of `__personality_routine`. With this patch one is also able to
build libc++abi with libunwind support on Windows.

Patch by Markus Böck!

Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 14798b44658c8b30b44afae20d0f391e88eb5bec
6 files changed