dont try figure out listen_service_fd position if unset

Signed-off-by: Andy Green <andy.green@linaro.org>
add static stack analysis

You can get a worst-first list of stack allocators like this

$ cat ./lib/.libs/*.su | sort -k2g | tac

On x86_64, currently the ones above 100 bytes are

server.c:126:5:lws_server_socket_service	4208	static
client.c:42:5:lws_client_socket_service	1584	static
libwebsockets.c:1539:1:libwebsocket_create_context	1136	static
libwebsockets.c:783:1:libwebsocket_service_fd	656	static
client-handshake.c:3:22:__libwebsocket_client_connect_2	592	static
libwebsockets.c:2149:6:_lws_log	496	static
server-handshake.c:33:1:handshake_0405	464	static
libwebsockets.c:2102:13:lwsl_emit_stderr	352	static
client.c:351:1:lws_client_interpret_server_handshake	240	static
daemonize.c:93:1:lws_daemonize	224	static
libwebsockets.c:434:1:libwebsockets_get_peer_addresses	208	static
client.c:694:1:libwebsockets_generate_client_handshake	208	static
output.c:534:5:libwebsockets_serve_http_file	192	static
output.c:51:6:lwsl_hexdump	176	static
sha-1.c:316:1:SHA1	160	static
libwebsockets.c:157:1:libwebsocket_close_and_free_session	144	static

Signed-off-by: Andy Green <andy.green@linaro.org>
use context service buffer instead of stack for server_socket_service

Reduces lws_server_socket_service from 4208 to 80 stack allocation
on x86_64

Signed-off-by: Andy Green <andy.green@linaro.org>
use context service buffer instead of stack for lws_client_socket_service

Signed-off-by: Andy Green <andy.green@linaro.org>