regexp/syntax: update perl script to preserve \s behavior
Incorporate https://code-review.googlesource.com/#/c/re2/+/3050/ from
the re2 repository. Description of that change:
Preserve the original behaviour of \s.
Prior to Perl 5.18, \s did not match vertical tab. Bake that into
make_perl_groups.pl as an override so that perl_groups.cc retains
its current definitions when rebuilt with newer versions of Perl.
This fixes make_perl_groups.pl to generate an unchanged perl_groups.go
with perl versions 5.18 and later.
Fixes #22057
Change-Id: I9a56e9660092ed6c1ff1045b4a3847de355441a7
Reviewed-on: https://go-review.googlesource.com/103517
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>