ciri: fix mariadb issues on Raspberry Pi (armv7)

[thibault-martinez]

Probably just need to add armv7 to the 32bits CPUs to rules_iota.

[oopsmonk]

Can you descript this issue in more details?

[thibault-martinez]

A first obvious issue is that armv7 is currently not part of the 32bits select of mariadb in rules_iota so it is considered as a 64bits platform. I tried to fix it but even after that some undefined behaviour
remained (e.g. random values returned by mariadb). Still investigating.