Strip socket options on cross-cscf repeat listens (v0.7.2)

Make the shared-listen-include pattern work with `reuseport` and the
other socket-level listen options. Nginx core enforces at-most-once
per sockaddr on options that set lsopt.set=1 (reuseport, bind,
backlog=, rcvbuf=, sndbuf=, setfib=, fastopen=, accept_filter=,
deferred, ipv6only=, so_keepalive=) and emits "duplicate listen
options for <addr>" otherwise. That rule collides with a single
listens.conf included from every vhost — each vhost's include
re-submits the same options.

The listen wrapper now detects the cross-cscf case, strips those
options from cf->args before delegating to the core handler, and
logs one notice per stripped listen. The first cscf owns the
options on the kernel socket; later cscfs merge cleanly via
ngx_http_add_server. Protocol-level flags (ssl, http2, quic,
proxy_protocol) pass through untouched since nginx OR-merges those
across cscfs.

This unblocks `reuseport` for deployments that want better
new-connection spread across workers.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/01-module/lab/server/nginx.conf

@@ -48,9 +48,14 @@ http {
     #     pair, so each server block gets its own cscf attached but no
     #     server block triggers nginx's "duplicate listen options"
     #     check;
+    #   * strip socket-level options (reuseport, bind, backlog=, ...)
+    #     from cross-cscf repeat sockaddrs — nginx enforces these
+    #     at-most-once per sockaddr, and the first cscf already owns
+    #     the single kernel socket that the remaining cscfs merge
+    #     into;
     #   * dedup bindings globally on (sockaddr, device), so init_module
-    #     creates exactly four sockets here (two families × two
-    #     devices) rather than 3 × 4 = 12.
+    #     creates exactly one binding per (device, family) rather than
+    #     one per (server block × device × family).
     # The default server owns the locations used by the traffic tests;
     # the two extras exist only to exercise the shared-include pattern.
     server {