Use toybox diff rather than local diff for builds.

Relevant upstream changes:
* diff -F, https://github.com/landley/toybox/commit/64952cee7002bc6f5c110d9979b3e6a2c33b62b8
* Line format options, https://github.com/landley/toybox/commit/9f5fb9ae9af14f651eb6920e96334e65e6b8cdd4

Change-Id: Iabefbdd3c5debe7b4960000336fd04e20750b93a
2 files changed