Bug#924036: statsmodels: KalmanFilter wrong results on armhf

[Rebecca N. Palmer]

Control: retitle -1 statsmodels: KalmanFilter wrong results on armhf
Control: found -1 0.9.0-2
Control: found -1 0.8.0-7

This is not a regression - it only looks new because the upstream tests 
weren't previously run.

Also reported as
https://bugs.launchpad.net/ubuntu/+source/statsmodels/+bug/1819227
I can't find an upstream report, but suspect this is because they don't 
test on non-x86.

As noted in the changelog, I attempted to disable this feature on armhf 
as I'd rather have an explicit error than silent nonsense. However, as 
it was an arch-specific patch applied at build time to a part of the 
package that is arch:all, it made the build-time tests pass but didn't 
actually do anything to the as-installed package.