proto/base: fix copy and paste bug in uwsgi_proto_base_cgi_prepare_headers

Reported by Coverity as CID #989253
core/exceptions: fix memory leak in wsgi_exception_setup_handlers

Reported by Coverity as CID #989249.
core/exceptions: fix leak in uwsgi_exception_handler_thread_loop

Reported by Coverity as CID #989248.
core/alarm: fix memory leak in uwsgi_alarm_thread_loop

Rpoerted by Coverity as CID #989247.
core/subscription: fix wrong check in uwsgi_subscribe2

It looks like both s2_server and s2_key are mandatory in
uwsgi_send_subscription so fail if any of them is missing not both.

Reported by coverity as CID #989245.
core/exception: avoid null pointer dereference in uwsgi_exception_run_handlers

If wsgi_req is NULL and uwsgi.reload_on_exception is True

Reported by Coverity as CID #989244.
plugins/router_http: Fix copy and paste bug in uwsgi_routing_func_http

Don't redeclare ub_url since it is already there.

Reported by Coverity as CID #989243, #989252.
Merge pull request #169 from xrmx/coverity8

More issues reported by Coverity