Bug#790358: please don't depend on clang-3.4

[Esa Peuha <esa.peuha@gmail.com>]

Package: kfreebsd-11
Control: block 783516 by -1

kfreebsd-11 currently depends on clang-3.4 which is going to be
removed (see bug #783516), so please update the dependency to a
newer version. Also, if possible, please do the same for kfreebsd-10.