In RNA pointer search buttons (i.e. the ones with an eyedropper),
data-blocks were handled badly. It was not possible to select a linked
data-block that had the same name as a local one, which is especially
common with library overrides. Neither was there a hint to tell appart
linked data-blocks and which .blend file they come from.
These issues are addressed now, we show an "L" prefix and the .blend
file name in the search box (like in ID-templates).
Changes here are quite simple, since the heavy lifting was already done
through c20c203b82.
Addresses T73156.
d6cefef98f