DDS: External Odometry overflows the timestamp

[tizianofiorenzani]

The function AP_DDS_External_Odom::handle_external_odom() converts the reported timestamp from microseconds (uint64) to ms (uint32). This causes an overflow when calculating time_ms.

https://github.com/ArduPilot/ardupilot/blob/master/libraries/AP_DDS/AP_DDS_External_Odom.cpp#L42

For example, it remote_time_us = 1769032352500220, time_ms = 3800825856

Suggestion

We can convert timestamp to time since boot right in place, accepting some minor jitter.

Platform
[ x ] All
[ ] AntennaTracker
[ ] Copter
[ ] Plane
[ ] Rover
[ ] Submarine