Revert "unix: fix stream refcounting buglet"

This change is making 45 out of 527 node.js tests fail on OS X with the
following assertion:

    Assertion failed: (!uv__is_active(handle)), function
    uv__finish_close, file ../../deps/uv/src/unix/core.c, line 165.

It's likely a manifestation of a bug elsewhere but, because there's a
new node.js release going out tonight, I'm reverting it for now.

This reverts commit 80f2f826bf90b84e659321c0b7fd8af419acb85e.

Conflicts:
	src/unix/stream.c