Fixing GCC-6 FTBS

[Peter Spiess-Knafl <dev@spiessknafl.at>]

Dear mentors!

I received some bugs on my packages about GCC-6 FTBS. I would like to
fix them and tried to install gcc-6 in a clean sid chroot using cowbuilder.

I added experimental to /etc/apt/sources.list and tried to install gcc-6
using

apt-get install gcc-6.

But the package manager won't install them giving the following error:

The following packages have unmet dependencies:
 gcc-6 : Depends: libcc1-0 (>= 6-20160117-1) but 5.3.1-6 is to be installed
         Depends: libgcc-6-dev (= 6-20160117-1) but it is not going to
be installed
E: Unable to correct problems, you have held broken packages.

Can someone help me out here? How is gcc-6 supposed to be installed in
cowbuilder?

Thank you and Greetings
Peter