[Interp] Fix include path retrieval on python3 (Debian Bug#750589 by Cristian Ionescu-Idbohrn <cristian.ionescu-idbohrn@axis.com>).
[Interp] Handle errors on python include path retrieval gracefully.
(Debian Bug#750589 by Cristian Ionescu-Idbohrn <cristian.ionescu-idbohrn@axis.com>)