Exclude LYPLG_TYPE_DIR and LYPLG_EXT_DIR from ly_config.h

[bgermann]

This is a follow-up on #1739 where it was suggested to removed the LYPLG_TYPE_DIR and LYPLG_EXT_DIR definitions from ly_config.h to make them Multi-Arch compatible. Please consider to make that change.

[michalvasko]

What change exactly? They cannot be removed so what do you suggest the alternative multi-arch path to be?