py-pyqt4: fix for the depends_lib reset caused by the Python PortGroup

[René J.V. Bertin]

On Sunday December 18 2016 04:23:11 Joshua Root wrote:

> > What do you suggest to recover from this mess?

> I would revert the last commit and remove port:qt4-mac from the 
> depends_lib-append on line 82.

I have a better suggestion: include the qt4 PG only where it's necessary. Currently the only reason py-pyqt4 doesn't have a qt4-mac depspec is because the python PG resets depends_lib. That's not very clean (neither of the python PG nor depending on it).
Testing now: configure went fine, the build will take a little while sadly.

R.