Update submodule ecl to latest Sun Aug 19 21:37:24 EDT 2018 (#10276)

- ecl in PX4/Firmware (5d5841de980ca2d108d52f4652a9437507652860): https://github.com/PX4/ecl/commit/35f628e68febc54abee801797da5f92612d89116
    - ecl current upstream: https://github.com/PX4/ecl/commit/34cd1366b715d80885d71f80c72cc5d0bfde64f0
    - Changes: https://github.com/PX4/ecl/compare/35f628e68febc54abee801797da5f92612d89116...34cd1366b715d80885d71f80c72cc5d0bfde64f0

    34cd136 2018-08-12 Daniel Agar - Jenkins update PX4BuildBot credential usage