[3.13] gh-127257: ssl: Raise OSError for ERR_LIB_SYS (GH-127361) (GH-127812)

gh-127257: ssl: Raise OSError for ERR_LIB_SYS (GH-127361)

From the ERR_raise manpage:

    ERR_LIB_SYS

        This "library code" indicates that a system error is
        being reported.  In this case, the reason code given
        to `ERR_raise()` and `ERR_raise_data()` *must* be
        `errno(3)`.

This PR only handles ERR_LIB_SYS for the high-lever error types
SSL_ERROR_SYSCALL and SSL_ERROR_SSL, i.e., not the ones where
OpenSSL indicates it has some more information about the issue.
(cherry picked from commit f4b31edf2d9d72878dab1f66a36913b5bcc848ec)

Co-authored-by: Petr Viktorin <encukou@gmail.com>