tls: fix hash calculations if client cert is requested and sent

tls: fix hash calculations if client cert is requested and sent

Symptoms: connecting to
    openssl s_server -cert vsftpd.pem -port 990 -debug -cipher AES128-SHA
works, but with "-verify 1" option added it does not.

function                                             old     new   delta
tls_xread_record                                     474     499     +25
tls_handshake                                       1582    1607     +25
bad_record_die                                        98     110     +12
tls_run_copy_loop                                    282     293     +11
tls_xread_handshake_block                             58      51      -7
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/1 up/down: 73/-7)              Total: 66 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>