Add libiberty-dev to prerequisites

Ubuntu and Debian have moved libiberty to a separate package.

Signed-off-by: Pekka Enberg <penberg@kernel.org>
Makefile: Add ncurses to LLVM libraries

As reported by Mathias Gaunard, LLVM seems to require ncurses on Ubuntu 14.04
but llvm-config does not specify that.

Signed-off-by: Pekka Enberg <penberg@kernel.org>