Crudely limit the use of 'k', 'K', 's' and 'S' when fuzzing.

Change-Id: I8f17b33b746c61bc5ab7ab59ee9e7f8660c2988f
Reviewed-on: https://code-review.googlesource.com/c/re2/+/59272
Reviewed-by: Perry Lorier <perryl@google.com>
Reviewed-by: Paul Wankadia <junyer@google.com>
(cherry picked from commit 123d379e288f3c113c26dca952d78ad5f4fc98fd)
Reviewed-on: https://code-review.googlesource.com/c/re2/+/59273
1 file changed