This reverts commit rB3a48147b8ab92, and fixes the issues with linking
etc.
Change compared to previous buggy commit (rBf8d219dfd4c31) is that
new `BlendFileReadReports` reports are now passed to the lowest level
function generating the `FileData` (`filedata_new()`), which ensures
(and asserts) that all code using it does have a valid non-NULL pointer
to a `BlendFileReadReport` data.
Sorry for the noise, it's always when you think a change is trivial and
do not test it well enough that you end up doing those kind of
mistakes...
The intention with this API function was to temporarily load
ID's tagged LIB_TAG_TEMP_MAIN,
however the way the `real_main` was used,
these ID's were loaded into the G.main.
This introduces two functions to the blenloader module, here shown as
calls for brevity:
* `temp_lib_ctx = BLO_library_temp_load_id(real_main, blend_file_path, idcode, idname, reports);`
* Now the data in `temp_lib_ctx->temp_id` can be used (but ought not to
be not assigned to non-temp datablocks).
* `BLO_library_temp_free(temp_lib_ctx);`
The first loads a datablock from a blend file, and returns it as part of
a `struct TempLibraryContext`. This struct contains the temp-loaded ID,
as well as enough information to correctly free everything again.
Differential Revision: https://developer.blender.org/D10736
