Fix helm build problem.

Check
https://github.com/emacs-helm/helm/commit/0f031b903063deef835aa6767431a7905e63f3d8
and https://github.com/emacs-helm/helm/issues/633 for details.
Let helm work without make on Windows

It's better to use the officially support build procedure, which is to
call make, but on Windows where we likely don't have make try to fake it
instead.

* recipes/helm.rcp (helm): :build/windows-nt just create helm-autoload.el
Merge pull request #1963 from npostavs/fix-helm-build-problem

Fix helm build problem