Passing from udp was not possible for the most part due to preread buffer
restriction.  Passing to udp could occasionally work, but the connection would
still be bound to the original listen rbtree, which prevented it from being
deleted on connection closure.

Previously a cycle in pass configuration resulted in stack overflow.

Previously, it could result when left-shifting signed integer due to implicit
integer promotion, such that the most significant bit appeared on the sign bit.

In practice, though, this results in the same left value as with an explicit
cast, at least on known compilers, such as GCC and Clang.  The reason is that
in_addr_t, which is equivalent to uint32_t and same as "unsigned int" in ILP32
and LP64 data type models, has the same type width as the intermediate after
integer promotion, so there's no side effects such as sign-extension.  This
explains why adding an explicit cast does not change object files in practice.

Found with UndefinedBehaviorSanitizer (shift).

Based on a patch by Piotr Sikora.

While copying ngx_http_variable_value_t structures to geo binary base
in ngx_http_geo_copy_values(), and similarly in the stream module,
uninitialized parts of these structures are copied as well.  These
include the "escape" field and possible holes.  Calculating crc32 of
this data triggers uninitialized memory access.

Found with MemorySanitizer.

Signed-off-by: Piotr Sikora <piotr@aviatrix.com>

The move makes the code look similar to the corresponding code in http module.

The FreeBSD SO_SETFIB support.

The FreeBSD accept filters support.

The Linux TCP_DEFER_ACCEPT support.

In preparation for adding more parameters to the listen directive,
and to be in sync with the corresponding structure in the http module.
No functional changes.