shiboken: Improve the libdir for windows

With virtualenv 20 we have the case where the first
path in the PYTHON_LIBRARIES cmake variable was wrong:
    a_virtual_env/libs/python3.lib
so the python code inside the helper didn't have a proper
check if the file was valid or it was just a wrong construct.

Additionally, the 'prefix' variable will contain the virtual
environment directory location, which will not contain the 'libs'
directory, because that's included in the system's installation path.
To solve this, we use the 'INCLUDEPY' directory, which is correct
as a base to create the real 'libs' one.

Task-number: PYSIDE-1231
Change-Id: Ifca08d74c49cd57572836a087edb96c089266dc7
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

0 files changed, 0 insertions, 0 deletions