EKFGSF_yaw::updateEKF() R_prev copy safely

[dagar]

Clang-tidy didn't like this. http://ci.px4.io:8080/blue/organizations/jenkins/PX4%2FFirmware/detail/PR-14301/4/pipeline

src/lib/ecl/EKF/EKFGSF_yaw.cpp:467:2: error: undefined behavior, source object type 'matrix::Dcmf' (aka 'Dcm<float>') is not TriviallyCopyable [bugprone-undefined-memory-manipulation,-warnings-as-errors]

         memcpy(&R_prev, &_ahrs_ekf_gsf[model_index].R, sizeof(R_prev));

[jkflying]

I believe Paul did this to reduce the number of copied data in GSF, since this happens 5x as much. Technically this could actually be reduced down to just 3 values, not a 2x3, since the second 3 get updated in-place, you just need the original value of the first 3 to not alias the multiplication with its own results.

[dagar]

That's also fine. Updated.

[jkflying]

Looks good, assuming the change indicator is fixed after a rebase.