update makeprg builder:
* it now accepts `fname`, `tail`, and `post_args` params.
* add some doc above syntastic#makeprg#build
* update a bunch of checkers to use the new params
Still have quite a few checkers that arent using makeprg#build.
Including all c* and a few other c-like checkers. And PHP.
Not to worried about c* as these checkers are complicated and probably
justify having their own logic to build makeprgs.
That variable specify the file which contains a list of filename that
Closure Compiler processes at once.
It can be useful for a project using 'require' statement like node.js.
