nginx: Update njs module to 0.5.0.

Changelog:
* nginx modules:

    *) Feature: introduced global "ngx" object.
      The following methods were added:
        ngx.log(level, msg)

      The following properties were added:
        ngx.INFO,
        ngx.WARN,
        ngx.ERR.

    *) Feature: added support for Buffer object where string
      is expected.

    *) Feature: added Buffer version of existing properties.
      The following properties were added:
      r.requestBuffer (r.requestBody),
      r.responseBuffer (r.responseBody),
      r.rawVariables (r.variables),
      s.rawVariables (s.variables).

      The following events were added in stream module:
      upstream (upload),
      downstream (download).

    *) Improvement: added aliases to existing properties.
      The following properties were added:
      r.requestText (r.requestBody),
      r.responseText (r.responseBody).

    *) Improvement: throwing an exception in r.internalRedirect()
      for a subrequest.

    *) Bugfix: fixed promise r.subrequest() with error_page redirect.

    *) Bugfix: fixed promise events handling.

* Core:

    *) Feature: added TypeScript definitions for built-in
      modules.
      Thanks to Jakub Jirutka.

    *) Feature: tracking unhandled promise rejection.

    *) Feature: added initial iterator support.
      Thanks to Artem S. Povalyukhin.

    *) Improvement: TypeScript definitions are refactored.
      Thanks to Jakub Jirutka.

    *) Improvement: added forgotten support for
      Object.prototype.valueOf() in Buffer.from().

    *) Bugfix: fixed heap-use-after-free in JSON.parse().

    *) Bugfix: fixed heap-use-after-free in JSON.stringify().

    *) Bugfix: fixed JSON.stringify() for arrays resizable via
      getters.

    *) Bugfix: fixed heap-buffer-overflow for
      RegExp.prototype[Symbol.replace].

    *) Bugfix: fixed returned value for Buffer.prototype.write*
      functions.

    *) Bugfix: fixed querystring.stringify().
      Thanks to Artem S. Povalyukhin.

    *) Bugfix: fixed the catch handler for
      Promise.prototype.finally().

    *) Bugfix: fixed querystring.parse().

(otis)