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.

This was supposed to check mx_list, not weight_list... oops.