Some changes:
* Set HOME to /root, since github mounts its own HOME and 'wine'
(because of permissions) and 'dub' (can't find packages) don't
like that.
* Remove the seccomp option, doesn't seem to be needed.
D lang compilers have an option -release (or similar) which turns off
asserts, contracts, and other runtime type checking. This patch wires
that up to the b_ndebug flag.
Fixes#7082
* xenial doesn't ship many dependencies, so make them all optional
since we don't guarantee that everything will work
* cmake/{5,6}: needs stdlib.h for EXIT_SUCCESS on GCC 5
* common/222: needs C++11, and GCC 5 doesn't understand `auto`
correctly unless we explicitly enable it.
* frameworks/1 boost: xenial doesn't ship boost_python3, so make it
properly optional
* frameworks/6 gettext: gettext can be installed without xgettext,
which doesn't cause the project to fail, but the installed files
list is different which causes the test to fail.
* frameworks/7 gnome: gobject-introspection can't be enabled because
the sanitizer unit test detects leaks in glib and fails
Nirbheek Chauhan
Christoph Reiter
Jussi Pakkanen
Michael Hirsch
Dylan Baker
Daniel Mensinger
Xavier Claessens