Since we need `headers_lc` as well as `headers_trim` in the following,
we do not release the former even if they are the same string, to avoid
complicating the release logic even more.

A new test case is not necessary, since we already have
mail_basic_alt2-win32.phpt and others.

If we're constructing extended-length paths (i.e. paths prefixed with
`\\?\`), we have to replace all forward slashes with backward slashes,
because the former are not supported by Windows for extended-length
paths.

The more efficient and likely cleaner alternative solution would be to
cater to this in `php_win32_ioutil_normalize_path_w()` by always
replacing forward slashes, but that might break existing code.  It
might be sensible to change that for `master`, though.

Since syslog's ident and facility parameters have been added to
config[1], vsyslog() segfaults on Windows, if openlog() has not been
called before.  We bring back the removed lines to fix this.

[1] <http://git.php.net/?p=php-src.git;a=commit;h=2475337bd8a0fad0dac03db3f5e7e9d331d53653>

* PHP-7.2:
  Fix erroneous assertions

Since PHP strings are binary safe (i.e. they may contain NUL bytes), we
must not assume that strlen()/wcslen() actually return the length of
the string.  Only if the given in_len is zero, it is safe to assert
this.

* PHP-7.2:
  Fix #77821: Potential heap corruption in TSendMail()

* PHP-7.1:
  Fix #77821: Potential heap corruption in TSendMail()

`zend_string_tolower()` returns a copy (not a duplicate) of the given
string, if it is already in lower case.  In this case we must not not
`zend_string_free()` both strings.  The cleanest solution is to call
` zend_string_release()` on both strings, which properly handles the
refcount.

To solve issues detected during testing, we backport the following
commits to PHP 7.2:

129c5c1181bf344b37e13fd6dc5dfe76c13d7208
9ac133a0b3863ca4d9659140154ee237e5f4669a
ce72bc6b658c335dd37393d0beb28584e6805e97