Fix breakage when RE2_USE_ICU is defined.

Change-Id: I095e9a07ddbced2fef1f05313277b10b42c9e73a
Reviewed-on: https://code-review.googlesource.com/c/re2/+/59133
Reviewed-by: Paul Wankadia <junyer@google.com>
(cherry picked from commit 068a6a822c02ddca5f87293c3be1896801921a40)
Reviewed-on: https://code-review.googlesource.com/c/re2/+/59134
1 file changed