This fixes a -Wshadow warning with an inline enum in regexp-compiler.cc.

Bug: v8:12244,v8:12245
Change-Id: I8b53a94a1945addb958b230abe01b10d4533edae
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3285732Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77935}