Work around a code generation issue seen with Clang.
Work around a code generation issue seen with Clang.

Change-Id: I06907160ae10d7a623f19454e5423bf8170b2593
Reviewed-on: https://code-review.googlesource.com/c/re2/+/58930
Reviewed-by: Paul Wankadia <62d4e38bb1380f055ec4b899baa75e52af09c5f7@google.com>

google/re2,google/re2,google/re2,google/re2,google/re2