scons tries to get build time vars by loading sysconfigdata. Inherit
python3native instead of using host python and unset
_PYTHON_SYSCONFIGDATA_NAME to avoid the need to depend on target
python3 for sysconfigdata when using scons to build.
Avoids build errors on still supported CentOS 7:
| DEBUG: Executing shell function do_compile
| scons: *** SCons version 3.0.5 does not run under Python version
3.4.8.
| Python 2.7 or >= 3.5 is required.
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
