respect argument order when compiling multiple files to stdout

I expected this to produce a JavaScript file containing the compiled output of each of the three source files in the specified order:

```make
dist/quux.js: src/foo.coffee src/bar.coffee src/baz.coffee
	@node_modules/.bin/coffee --compile --print $+ > $@
```

Apparently this usage was not anticipated, as order in which the compiled code is written to stdout in nondeterministic (i.e. not necessarily _foo_ then _bar_ then _baz_).