uboot-tools: disable libfdt swig wrapper
The current tools build assumes the host system when trying to detect if
swig/python are present. It then uses those tools from the path.
The upstream RFC included this commit set's patch but offered up
discussion on how to cleanly introduce a better method for detecting
swig and using the tools. The tools build really needs to be sysroot
and prefix/host dir tools aware.
Upsteam submission for RFC:
https://lists.denx.de/pipermail/u-boot/2017-May/289520.html
Workaround for:
http://autobuild.buildroot.net/results/
6d52ac8bb71012aea6fc4c679691b31a3366728b
Signed-off-by: Matthew Weber <matthew.weber@rockwellcollins.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>