*/*: update NGINX JavaScript: 0.8.3 -> 0.8.4 (+)

<ChangeLog>

nginx modules:

*) Feature: allowing to set Server header for outgoing headers.

*) Improvement: validating URI and args arguments in r.subrequest().

*) Improvement: checking for duplicate js_set variables.

*) Bugfix: fixed clear() method of a shared dictionary without

timeout introduced in 0.8.3.

*) Bugfix: fixed r.send() with Buffer argument.

Core:

*) Feature: added QuickJS engine support in CLI.

*) Bugfix: fixed atob() with non-padded base64 strings.

</ChangeLog>