libz160: new package

An API for user space programs to perform 2D accelerated graphics operations
on AMD GPU

[Thomas:
 - merge in the same patch the patch switching to the freescale-imx
   extract helper.
 - remove the dependency on "depends BR2_arm", since anyway the
   package Config.in file is only included if we are using the i.MX51
   or i.MX53 platforms.
 - use full installation paths (i.e $(INSTALL) -D), and install
   libraries 755, as it usually done.]

Signed-off-by: Jérôme Pouiller <jezz@sysmic.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>