Bump minimum re2c version to 0.13.7

[cmb69]

We recently merged PR #6464, but that fix actually requires re2c 0.13.7 (released 2014-07-25), while the current requirement of PHP-8.0 is re2c 0.13.4 (released 2008-04-05). That bugfix has been reverted from PHP-7.4.14, because PHP 7.4 is packaged with re2c 0.13.5, but PHP 8.0.0RC1 has it, becaused it's packaged with re2c 0.16.0. Given that users building from the release tarballs would not be affected by this re2c version bump at all, and that the minimum required version has been released more than six years ago, in my opinion this late requirements bump is acceptable.

@sgolemon, @carusogabriel, what do you think?

[carusogabriel]

Given the reasons, I should say it's not a problem on doing it!

[rlerdorf]

We recently merged PR #6464, but that fix actually requires re2c 0.13.7 (released 2014-07-25), while the current requirement of PHP-8.0 is re2c 0.13.4 (released 2008-04-05). That bugfix has been reverted from PHP-7.4.14, because PHP 7.4 is packaged with re2c 0.13.5, but PHP 8.0.0RC1 has it, becaused it's packaged with re2c 0.16.0. Given that users building from the release tarballs would not be affected by this re2c version bump at all, and that the minimum required version has been released more than six years ago, in my opinion this late requirements bump is acceptable.

@sgolemon, @carusogabriel, what do you think?

Note that the old way of having a default rule was to use [^] instead of * which should work for PHP 7.4 without bumping the re2c version. See http://re2c.org/manual/warnings/undefined_control_flow/wundefined_control_flow.html#the-old-default-rule

[rlerdorf]

By the way, 8.0.1 went out without this re2c version bump: https://github.com/php/php-src/blob/PHP-8.0.1/configure.ac#L157
which means distro folks and people doing full automated koji builds aren't able to build PHP 8.0.1 on older distros like Centos 7 that still ship with re2c 0.13.5.

[cmb69]

Thanks, @rlerdorf. Unfortunately, using <NORMAL>[^] instead of <NORMAL>* breaks phpdbg; e.g. quit is no longer accepted. Probably best to revert all that: PR #6593.