issue with path in makefile for stan/version.hpp

[bob-carpenter]

Rob Goedman reports on stan-users:

I noticed below warning messages. The file is clearly available, but 1 level deeper 
( .../cmdstan/stan/src/stan/version.hpp).

From https://github.com/stan-dev/cmdstan
 * branch            develop    -> FETCH_HEAD
Already up-to-date.

$ make stan-update
grep: /Users/rob/Projects/Stan/cmdstan/src/stan/version.hpp: No such file or directory
grep: /Users/rob/Projects/Stan/cmdstan/src/stan/version.hpp: No such file or directory
grep: /Users/rob/Projects/Stan/cmdstan/src/stan/version.hpp: No such file or directory
git submodule init
git submodule update

[syclik]

This only happens when the Stan submodule is uninitialized; when cloned directly from GitHub, the stan folder is empty. After running make stan-update, the Stan submodule should be filled and the error messages from grep goes away.

I'm going to close this issue for now since it's a difficult fix (I think) since I don't know how to take care of it offhand. It also goes away once the Stan submodule is updated, so it isn't a big deal (for now). If it ends up confusing a lot of users, we'll reopen the issue and address it.