- these only run if code coverage is enabled

Since SBUS does not have CRC, we can use timing information to improve
parsing reliability and reject unexpected bytes.

 - <cfloat> isn't available in the NuttX c++ library

 - <cinttypes> isn't available in the NuttX c++ library

 - Fixes #11134

 - fixes #11125

- Don't duplicate the ret variable to err.
- Return -1 on any error, 0 otherwise.
- Set errno to return value of pthread_cond_timedwait.

The API of cond_timedwait was wrong. It used return -1 and set errno
instead of returning the error as specified for pthread_cond_timedwait
which it tries to mock.

Previous commit 98ae0186 changed the err variable to errno, which is not the return value we are looking for.

- fixes #11009

fix home position timestamp to be the timestamp that the home was set and not when the message was sent

zeroed uninitialized fields on home_position, mavlink_rc_channels_override, mavlink_mission_item, mavlink_mission_item_int

It turns out that `sendto` does not work for TCP on Cygwin-Windows,
instead we need to use `send`. This required some refactoring since we
need to have the internet protocol and the port stored as a member
variable.

This should fix that lockstep SITL simulation was not working on
Windows.

    - sitl_gazebo in PX4/Firmware (1f9b8333): https://github.com/PX4/sitl_gazebo/commit/c90e8ad2b27b95dc0b4c45b346509477c5fa593d
    - sitl_gazebo current upstream: https://github.com/PX4/sitl_gazebo/commit/e945745021a74ae45695a624dfc114a5c7bbd6bc
    - Changes: https://github.com/PX4/sitl_gazebo/compare/c90e8ad2b27b95dc0b4c45b346509477c5fa593d...e945745021a74ae45695a624dfc114a5c7bbd6bc

    e945745 2018-12-26 Julian Oes - worlds: fix rate for tailsitter and plane
46a3d27 2018-12-14 Jörg Schmidt - Fix bug in groundtruth altitude calculation