Adjust debian packaging as in other Osmocom projects to not compress the
pdf files.
Related: SYS#6855
Change-Id: I4372c2d93b317a9deaed3650941c7438accf9211
In Change-Id I87c68e8d14f8ddb6054178118ff1f96216483f5c we introduced
a hack to fix 'make distcheck' which in turn broke debian packaging.
Let's make sure the latter works while the formar also still does.
Change-Id: I16f7d0e8b7f63ed58dd4939c88e5276185bc3178