acpi: Re-license ACPI builder files from GPLv2 to LGPLv2.1

acpi: Re-license ACPI builder files from GPLv2 to LGPLv2.1

ACPI builder is currently distributed under GPLv2 license.

We plan to make the builder available to components other than the
hvmloader (which is also GPLv2). Some of these components (such as
libxl) may be distributed under LGPL-2.1 so that they can be used by
non-GPLv2 callers.  But this will not be possible if we incorporate
the ACPI builder in those other components.

To avoid this problem we are relicensing sources in ACPI bulder
directory to the Lesser GNU Public License (LGPL) version 2.1

gpl/mk_dsdt_asl.sh file will remain GPL-only pending permission to
relicense from Lenovo due to commit 801d469ad ("[HVM] ACPI support
patch 3 of 4: ACPI _PRT table."))

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Acked-by: Daniel Kiper <dkiper@net-space.pl>
Acked-by: Stefan Berger <stefanb@us.ibm.com>
Acked-by: Kouya Shimura <kouya@jp.fujitsu.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Keir Fraser <keir@xen.org>
Acked-by: Simon Horman <horms@verge.net.au>
Acked-by: Lars Kurth <lars.kurth@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> [for Oracle, VirtualIron and Sun contributions]