Bug#1009191: cctbx: please re-enable building on riscv64

[Graham Inggs]

Source: cctbx
Version: 2021.12+ds1-3

Hi Maintainer

Building on riscv64 was silently disabled in 2021.12+ds1-3.
2021.12+ds1-2 built successfully in the past [1], and 2021.12+ds1-4
continues to build in Ubuntu.

Please re-enable building on riscv64 as we would like to promote
riscv64 to a release architecture.

Regards
Graham


[1] https://buildd.debian.org/status/logs.php?pkg=cctbx&arch=riscv64