package/acpica: add host package

Add support to build the ACPICA package for the host. This is useful
for the iasl command which is required to build some packages,
including Xen tools.

This is a necessary requirement before changing the Xen package to
address:

  http://autobuild.buildroot.net/results/afa199864d6b546fe759bb582a9c10702ea7fa78/



Signed-off-by: Alistair Francis <alistair.francis@xilinx.com>
Acked-by: Erico Nunes <nunes.erico@gmail.com>
[Thomas: use PREFIX= and not DESTDIR= for host installation, tweak
commit log.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>