sockaddr: properly decode sockaddr_hci addresses without hci_channel

sockaddr: properly decode sockaddr_hci addresses without hci_channel

Before Linux commit v2.6.38-rc1~476^2~14^2~3^2~43^2~9,
struct sockaddr_hci did not contain hci_channel field.

* configure.ac (AC_CHECK_HEADERS([bluetooth/bluetooth.h])): Add check
for struct sockaddr_hci.hci_channel.
* sockaddr.c (print_sockaddr_data_bt): Decode struct sockaddr_hci
without hci_channel field.
* tests/net-sockaddr.c (check_hci): Add check for struct sockaddr_hci
decoding without hci_channel field; guard hci_channel with #ifdef
HAVE_STRUCT_SOCKADDR_HCI_HCI_CHANNEL.
(check_raw): Remove "len++", as 4-byte AF_BLUETOOTH socket addresses are
interpreted as struct sockaddr_hci without hci_channel field.