This func is long enough, there's no real need to make it even longer with
verbose local varnames and multi-line for loops...
Also, avoid mono-leters names as well for data pointers.
Root of the issues comes to the fact that it's possible to produce
a situation when library object data uses local object. This is
actually forbidden and not supported by .blend IO.
Made it so Make Local wouldn't produce such an unsupported states.
Reviewers: brecht
Differential Revision: https://developer.blender.org/D372