Copter: Give better error in opendroneid build when DID_ENABLE=0.
Based on my report on discord:
Problem arises when:
- ArduPilot compiled with
--enable-opendroneid -
DID_ENABLEset to 0 - init and update functions do not do anything but pre_arm_checks still fail.
Should pre_arm_checks also be skipped or there should be a different error message like DID_ENABLE is not allowed to be 0 when compiled with --enable-opendroneid.
Currently one of the pre_arm_checks will fail but there's no indiciation of what exactly the problem is. A better error message or disabling pre arm checks might save time for users.
This PR adds a better error message to report that DID_ENABLE is not allowed to be 0 when compiled with --enable-opendroneid.
@shipp02 I've squashed commits together and fixed a whitespace change problem.
Can you state exactly what the prearm-failure you were getting before this PR?