Use a function pointer rather than lambda when loading unwinding
functions on Windows.

Bug: v8:7301
Change-Id: I00e9c895d9ffdce6ba485eaf4401a749faa5e825
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2867489Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#74359}