Make "front and back" prefix accel work with MSVC.
Make "front and back" prefix accel work with MSVC.

Change-Id: Idbae09ca9a97c1f8ce08ddefd0bb2863d4deb325
Reviewed-on: https://code-review.googlesource.com/c/re2/+/56774
Reviewed-by: Paul Wankadia <62d4e38bb1380f055ec4b899baa75e52af09c5f7@google.com>

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