The fix in https://crrev.com/c/3283620 doesn't work, it was meant to be
a general way to fix shadow whenever ASM_CODE_COMMENT is used, by
appending the current line, via __LINE__ macro to the variable name.
However, __LINE__ is not expended correctly when it is directly part of
a variable name.

To fix the shadowing, we use UNIQUE_IDENTIFIER to give unique names.

Bug: v8:12244,v8:12245
Change-Id: I7b9b9da74d62023ac631ff0876f41e80971e2f09
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3291804
Auto-Submit: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78058}