child_process: check execFile and fork args

Port of joyent/node commits:

 * https://github.com/nodejs/node-v0.x-archive/commit/e17c5a72b23f920f291d61f2780068c18768cb92
 * https://github.com/nodejs/node-v0.x-archive/commit/70dafa7b624abd43432e03304d65cc527fbecc11



Pull over test-child-process-spawn-typeerror.js from v0.12, replacing
the existing test in master. The new test includes a broader set of
tests on the various arg choices and throws.

Reviewed-By: trevnorris - Trevor Norris <trevnorris@nodejs.org>
Reviewed-By: cjihrig - Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: thefourtheye - Sakthipriyan Vairamani
PR-URL: https://github.com/nodejs/node/pull/2667
Fixes: https://github.com/nodejs/node/issues/2515