D15070: Bindings: Query the install directory from python

[Stefan Brüns]

bruns added a dependency: D15867: Bindings: Remove INSTALL_DIR_SUFFIX from 
ecm_generate_python_binding.

REPOSITORY
  R240 Extra CMake Modules

REVISION DETAIL
  https://phabricator.kde.org/D15070

To: bruns, #frameworks
Cc: cgiboudeaux, bcooksley, kde-frameworks-devel, kde-buildsystem, michaelh, 
ngraham, bruns