* USD and OpenVDB headers use deprecated TBB headers, suppress all deprecation
warnings there since we have no control over them.
* For our own TBB includes, use the individual headers rather than the tbb.h that
includes everything to avoid warnings, rather than suppressing all.
This is in anticipation of the TBB 2020 upgrade in D10359. Ref D10361.
Add TBB::flow graph scheduling to BLI_task.
Using flow graphs, a graph of nodes (tasks) and links can be defined.
Work can flow though the graph. During this process the execution of the nodes will be
scheduled among the available threads.
We are planning to use this to improve the threading in the draw manager.
The implemented API is still limited it only supports sequential flows. Joins and buffers
are not supported. We could eventually support them as part of an CPP API. These features
from uses compile time templates and are hard to make a clean C-API for this.
Reviewed By: Sergey Sharybin, Brecht van Lommel
Differential Revision: https://developer.blender.org/D7578