Revert "net: correct sk_acceptq_is_full()"

Revert "net: correct sk_acceptq_is_full()"

This reverts commit f211ac154577ec9ccf07c15f18a6abf0d9bdb4ab.

We had similar attempt in the past, and we reverted it.

History:

64a146513f8f12ba204b7bf5cb7e9505594ead42 [NET]: Revert incorrect accept queue backlog changes.
8488df894d05d6fa41c2bd298c335f944bb0e401 [NET]: Fix bugs in "Whether sock accept queue is full" checking

I am adding a fat comment so that future attempts will
be much harder.

Fixes: f211ac154577 ("net: correct sk_acceptq_is_full()")
Cc: iuyacan <yacanliu@163.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>