Produce symlink into builddir on VPATH?

[Rhys Ulerich]

Other than resorting to the shell in a target, is there a way to cause
Automake to produce a symlink from the source tree into the build tree
if-and-only-if the build is VPATH?

I've some non-generated Python code (srcdir) relying on generated
Python code (builddir) and I'd like to be able to just use it from the
builddir (hence the symlink from srcdir) without monkeying with
PYTHONPATH.

Thanks,
Rhys