coreutils 6.9: disable native

ERROR: The recipe coreutils-native is trying to install files into a shared area when those files already exist. Those files and their manifest location are:
   tmp/sysroots/x86_64-linux/bin/kill
 Matched in manifest-x86_64-util-linux-native.populate_sysroot

We have 8.23, so disable it rather than fix.

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>