Bug#912544: libomp-7-dev: conflicts with libomp-dev which depends on it

[Sven Joachim]

Package: libomp-7-dev
Version: 1:7-6
Severity: serious

In the latest llvm-defaults upload libomp-dev depends on libomp-7-dev, but
libomp-7-dev conflicts with libomp-dev, so the latter is not installable.