Without these these files cannot be included on their own. https://github.com/ceres-solver/ceres-solver/issues/410 Change-Id: I87ca91d15f5ab2053e43480ecbde74779125c709
This adds a callback mechanism to for users to get notified just before jacobian and residual evaluations. This will enable aggressive caching and sharing of compute between cost functions. Change-Id: I67993726920218edf71ab9ae70c34c204756c71a