This fixes GHSA-54hq-v5wp-fqgv DOS vulnerabality by limitting number of
parsed multipart body parts as currently all parts were always parsed.

PHP’s implementation of crypt_blowfish differs from the upstream Openwall
version by adding a “PHP Hack”, which allows one to cut short the BCrypt salt
by including a `$` character within the characters that represent the salt.

Hashes that are affected by the “PHP Hack” may erroneously validate any
password as valid when used with `password_verify` and when comparing the
return value of `crypt()` against the input.

The PHP Hack exists since the first version of PHP’s own crypt_blowfish
implementation that was added in 1e820ec.

No clear reason is given for the PHP Hack’s existence. This commit removes it,
because BCrypt hashes containing a `$` character in their salt are not valid
BCrypt hashes.

Fix it by extending the array sizes by one character. As the input is
limited to the maximum path length, there will always be place to append
the slash. As the php_check_specific_open_basedir() simply uses the
strings to compare against each other, no new failures related to too
long paths are introduced.
We'll let the DOM and XML case handle a potentially too long path in the
library code.