Justify RAW_PTR_EXCLUSION in CTLogInfo

The pointer member in CTLogInfo is currently unused (always null),
but may be used in the future. However, it is only ever set by the
autogenerated log_list-inc.cc file, and only ever to a statically-
allocated array. Hence it cannot dangle, and so we don't need to
incur the overhead of replacing it with a raw_ptr.

Bug: 346693916
Change-Id: I1912429840366f4a97519579208a8016c1d7a479
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6087773
Reviewed-by: Chris Thompson <cthomp@chromium.org>
Commit-Queue: Devon Loehr <dloehr@google.com>
Cr-Commit-Position: refs/heads/main@{#1395059}