[Debian-med-packaging] arb is marked for autoremoval from testing

[Debian testing autoremoval watch]

arb 6.0.6-4 is marked for autoremoval from testing on 2018-09-13

It (build-)depends on packages with these RC bugs:
891690: libclang-common-4.0-dev: /usr/lib/llvm-4.0/lib/clang/4.0.1/lib/ is empty on mipsel
897804: llvm-toolchain-4.0: ftbfs with GCC-8