Also add some helper macros for PROTECT/UNPROTECT that check for
IMMUTABLE. These checks are needed for nearly any use of
PROTECT/UNPROTECT.

_php_mb_match_regex() is supposed to return != 0 on success, and 0 on
failure.  pcre2_match() returns >= 0 on success, and < 0 on failure.
We map the result accordingly.

Since this patch fixes four failing tests, there is no need to add
another.

* PHP-7.2:
  Fix #76704: mb_detect_order return value varies based on argument type

* PHP-7.1:
  Fix #76704: mb_detect_order return value varies based on argument type

php_mb_parse_encoding_list() and php_mb_parse_encoding_array() are
supposed to return SUCCESS and FAILURE, not 1 and 0, respectively.

The $Id$ keywords were used in Subversion where they can be substituted
with filename, last revision number change, last changed date, and last
user who changed it.

In Git this functionality is different and can be done with Git attribute
ident. These need to be defined manually for each file in the
.gitattributes file and are afterwards replaced with 40-character
hexadecimal blob object name which is based only on the particular file
contents.

This patch simplifies handling of $Id$ keywords by removing them since
they are not used anymore.

Since commit ea83b69[1] changed the type of mbstring.strict_detection
from `long` to `zend_bool`, we have to update the `on_modify` callback
as well.

[1] http://git.php.net/?p=php-src.git;a=commit;h=ea83b69883f3f77fd27e4663fa854c88f141ab41