The title says it all, move the EWA filter to BLI (currently it's math_interp.c) and use the function from both BI renderer and the compositor. This makes more central place of the algorithm, allowing to have fixes and optimizaitons synchronized across the two usages. This also fixes T41440: Displacement in compositing creates holes Reviewers: campbellbarton, lukastoenne Reviewed By: lukastoenne Maniphest Tasks: T41440 Differential Revision: https://developer.blender.org/D748