The recent python build fix for MAC removed hardcoded paths to
clone/libs-extern-sys/python/unxlngi6.pro/misc/build/python-inst
The result is that we need to set PYTHONHOME. Also we need to add
python/lib-dynload into PYTHONPATH
This commit also cleans up the condition for SYSTEM_TRANSLATE_TOOLKIT.
It removed the ugly "$(AUGMENT_LIBRARY_PATH) $(WRAPCMD)" when the system
toolkit is used.
--skipsource also does the fallback to en-US when a translation
is missing so for example we are not flawed by incomplete localized
printing dialogs any more (see fdo#33189)
