Move SO_ACCEPTFILTER and TCP_DEFER_ACCEPT checks into configure.

NetBSD 5.0+ has SO_ACCEPTFILTER support merged from FreeBSD, and having
accept filter check in FreeBSD-specific ngx_freebsd_config.h prevents it
from being used on NetBSD.  Therefore move the check into configure (and
do the same for Linux-specific TCP_DEFER_ACCEPT, just to be in line).

src/core/ngx_connection.c

@@ -580,7 +580,7 @@ ngx_configure_listening_sockets(ngx_cycle_t *cycle)
             {
                 ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                               "setsockopt(SO_ACCEPTFILTER, \"%s\") "
-                              " for %V failed, ignored",
+                              "for %V failed, ignored",
                               ls[i].accept_filter, &ls[i].addr_text);
                 continue;
             }

src/os/unix/ngx_freebsd_config.h

@@ -92,11 +92,6 @@ typedef struct aiocb  ngx_aiocb_t;
 #define NGX_LISTEN_BACKLOG        -1
 
 
-#if (defined SO_ACCEPTFILTER && !defined NGX_HAVE_DEFERRED_ACCEPT)
-#define NGX_HAVE_DEFERRED_ACCEPT  1
-#endif
-
-
 #if (__FreeBSD_version < 430000 || __FreeBSD_version < 500012)
 
 pid_t rfork_thread(int flags, void *stack, int (*func)(void *arg), void *arg);

src/os/unix/ngx_linux_config.h

@@ -96,11 +96,6 @@ typedef struct iocb  ngx_aiocb_t;
 #define NGX_LISTEN_BACKLOG        511
 
 
-#if defined TCP_DEFER_ACCEPT && !defined NGX_HAVE_DEFERRED_ACCEPT
-#define NGX_HAVE_DEFERRED_ACCEPT  1
-#endif
-
-
 #ifndef NGX_HAVE_SO_SNDLOWAT
 /* setsockopt(SO_SNDLOWAT) returns ENOPROTOOPT */
 #define NGX_HAVE_SO_SNDLOWAT         0