Bug#1087965: tachyon: build-depends on libopenmpi-dev on 32-bit architectures

[Santiago Vila]

> I have uploaded the following debdiff to fix this issue, in order to unblock the 
> openmpi 5 transition.

Thanks for the patch.

I've just made a team upload which supersedes the NMU.

For simplicity, I've removed the NMU from history, but your changes
are appropriately credited in the changelog.

Thanks.