tools: remove obsolete lint config file

All JS files have been moved out of the `src` directory so the
`.eslintrc` file in that directory can also be removed.

PR-URL: https://github.com/nodejs/node/pull/5959
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Roman Klauke <romankl@users.noreply.github.com>

src/.eslintrc

@@ -1,6 +0,0 @@
-rules:
-  # ECMAScript-6
-  # http://eslint.org/docs/rules/#ecmascript-6
-  prefer-template: 2
-  # Custom rules in tools/eslint-rules
-  buffer-constructor: 2