PDO driver constructors are throwing PdoException without setting
errorInfo, so create a new reusable function that throws exceptions
for PDO and will also set the errorInfo. Use this function in
pdo_mysql, pdo_sqlite, and pdo_pgsql.

Different manufacturer models may come with a
different endianness (motorola/intel) format. In
order to avoid a big refactor and a gigantic lookup
table, this commit simply attempts to switch the
endianness and proceed when values are acceptable.

Closes GH-5849.

Whether the type library is cached is actually irrelevant here; what
matters is that the symbols are imported, and since these are not
cached, we have to import them for every request.  And we cannot cache
the symbols, because the import depends on the current codepage, but
the codepage is a `PHP_INI_ALL` setting.

One branch did not release tmp_replace_entry_str.

Also reduce the scope of some variables.

Only return true from dns_get_mx if we actually found any MX record.

We must not call `zend_list_delete()` in resource closer functions
exposed to userland, because decreasing the refcount there leads to
use-after-free scenarios.  In this case, commit 4a42fbb worked for
typical use-cases where `xml_parser_free()` has been called exactly
once for the resource, because there is an internal zval (`->index`)
referencing the same resource which already increased the refcount by
one.  However, when `xml_parser_free()` is called multiple times on the
same XML parser resource, the resource would be freed prematurely.

Instead we forcefully close the resource in `xml_parser_free()`.  We
also could decrease the refcount of the resource there, but that would
require to call `xml_parser_free()` which is somewhat uncommon, and
would be particularly bad wrt. PHP 8 where that function is a NOP, and
as such doesn't have to be called.  So we do no longer increase the
refcount of the resource when copying it to the internal zval, and let
the usualy refcounting semantics take care of the resource destruction.

[1] <http://git.php.net/?p=php-src.git;a=commit;h=4a42fbbbc73aad7427aef5c89974d1833636e082>

Closes GH-5940.

Fixes the function `next_newline()` in zend_language_scanner.l. The
function now correctly returns a newline_len of 2 for "\r\n".

Closes GH-5944.