uninative: Fix conflicts with normal sysroot

uninative: Fix conflicts with normal sysroot

Currently this code installs into the standard sysroot, however this causes
some conflicts when linking since the linker can look specifically for
versioned .so files (e.g. like libpthreads.so.0). This breaks builds
of util-linux-native for example.

The easiest solution is to install uninative into its own separate sysroot.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>