[Debian-med-packaging] Bug#982365: ball: reduce Build-Depends

[Helmut Grohne]

Source: ball
Version: 1.5.0+git20180813.37fc53c-6
Severity: minor

src:ball has a lot of dependencies. I looked into them, because it
cannot be cross built. While looking into this, I found a number of
dependencies that are unused (even though dropping them likely doesn't
help cross building). Given that ball is normally reproducible, I
compared the resulting artifacts of a regular full build with a nocheck
build that has the following dependencies moved from Build-Depends to
Build-Conflicts:
 * qttools5-dev
 * libfftw3-dev
 * libgsl0-dev
 * libxrender-dev
 * libboost-math-dev
 * libboost-system-dev
 * libasio-dev
 * libboost-regex-dev
 * libxmu-dev

That's quite a pile of dependencies. They can show up here for a number
of reasons that are slightly difficult to tell apart:
 * Really unused. In such cases, it is best to delete them.
 * Only used for unit tests (which are disabled by
   DEB_BUILD_OPTIONS=nocheck in the second build). In such cases, they
   should be annotated <!nocheck>.
 * In rare cases a dependency is vendored and a system copy is used when
   available. In such cases, it is best to keep the dependency.
   Optionally, steps can be taken to avoid accidental uses of the vendor
   copy. For example, the vendor copy can be deleted or sometimes a flag
   can be passed to the build system.

When dropping any other dependency, either the build fails or the output
artifact differs.

Please reduce your build dependencies either by dropping dependencies
mentioned above or annotating them <!nocheck>.

Helmut