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.