Change unix_diag requests back to use full dump instead of exact match

Change unix_diag requests back to use full dump instead of exact match

Unfortunately, 64-bit linux kernel has a bug in matching inode numbers
greater than INT_MAX, so unix_diag exact match is not reliable.

This partially reverts commit 69bfc89770152033d4aa0bc5673fc46e65d89838.

* socketutils.c (unix_send_query): Add NLM_F_DUMP to nlmsg_flags,
remove initialization of udiag_cookie.
* tests/netlink_unix_diag.c (send_query): Remove "inode" argument,
add NLM_F_DUMP to nlmsg_flags, remove initialization of udiag_ino
and udiag_cookie.
(check_responses): Remove "inode" argument and its use.
(main): Remove invocation of inode_of_sockfd and passing of listening
socket inode to send_query and check_responses.