vtkpython: add site-packages to the path

Now that mpi4py lives there, look for modules there as well.

Change-Id: I6e815a0ea31cfc264cdcf74c180f8b8d6a9aa362
import mpi4py 1.3

v=1.3
githash=f2db7face09dda17da04c5276b78095830743c3c

Source copied from ParaView's ThirdParty module.

Change-Id: I489b8e9026cd0fde3bdd4218d4e2b5ddc1f252ce
Merge branch 'mpi4py-upstream' into add-mpi4py-third-party

* mpi4py-upstream:
  import mpi4py 1.3

Change-Id: Ida86f20103ad9f5ef60e93c08a10d5d039964413
mpi4py: add module information

Change-Id: Ibf3befb2491b9a04651462a10a5dc68c515b214d
Merge topic 'add-mpi4py-third-party'

647b8907 mpi4py: add module information
f39c1284 Merge branch 'mpi4py-upstream' into add-mpi4py-third-party
aa8f6a08 import mpi4py 1.3
0843035a vtkpython: add site-packages to the path

Change-Id: I934194e8a94c4e1c16e72b59981cecc32253185d