build: use shorthand lint target from test

Instead of invoking jslint/cpplint from the test target,
call on the generic lint instead since it checks if eslint
exists. Since our tarballs lacks eslint we now get a more graceful
exit from `make test` instead of a traceback from jslint.

PR-URL: https://github.com/nodejs/node/pull/6406
Fixes: https://github.com/nodejs/node/issues/6408


Reviewed-By: Ryan Graham <r.m.graham@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>