I made some changes to src:ball on top of the existing commits, fixing the RC bugs (#1112717, #1114056), #1040385 and some other subtle issues (no .so symlinks in -dev packages, missing dependencies).
The reprotest job timed out so the time limit should be bumped in the project's settings. It will fail anyway; I enumerated the remaining issues in reproducibility.patch. I also successfully cross-built the package on amd64 for ppc64el (which was not possible before as it called cmake directly and didn't pass the necessary options for cross-building).
