grep: Update to version 3.7

grep: Update to version 3.7

- Update from 3.6 to 3.7
- Update of rootfile not required
- Changelog
   * Noteworthy changes in release 3.7 (2021-08-14) [stable]
     ** Changes in behavior
        Use of the --unix-byte-offsets (-u) option now evokes a warning.
        Since 3.1, this Windows-only option has had no effect.
     ** Bug fixes
        Preprocessing N patterns would take at least O(N^2) time when too many
         patterns hashed to too few buckets. This now takes seconds, not days:
         : | grep -Ff <(seq 6400000 | tr 0-9 A-J)
         [Bug#44754 introduced in grep 3.5]
- More details of the changes can be found in the ChangeLog file in the source tarball.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>