This patch fixes:
- the call of LibFree on a unfinished loaded library;
- memory leak created on end of game : the async libraries are loaded but not converted, so not freed with the master scene.
Reviewers: campbellbarton, sybren, youle, hg1, moguri, lordloki
Reviewed By: moguri, lordloki
Differential Revision: https://developer.blender.org/D1571