Blender Git Loki

Fix T52481: After making all local, local proxies of linked data get broken after file save and reload.

Issue was nasty hidden one, the dual status (mix of local and linked)
of proxies striking again.

Here, remapping process was considering obdata pointer of proxies as
indirect usage, hence clearing the 'LIB_TAG_EXTERN' of obdata pointer.
That would make savetoblend code not store any 'lib placeholder' for
obdata data-block, which was hence lost on next file read.

Another (probably better) solution here would be to actually consider
obdata of proxies are fully indirect usage, and simply reassign proxies
from their linked object's obdata on file read...

However, that change shall be safer for now, probably good for 2.79 too.