nativesdk-coreutils: a lot of warnings fixed

nativesdk-coreutils: a lot of warnings fixed

When we create nativesdk-coreutils, a lot of warnings appear,it
show many files can't find. Because in the coreutils recipe, it
didn't contain the do_install for the nativesdk, so when the
alternative system check the files in the following process, it
can't find the files. So we should add the do_install for the
nativesdk, change the function do_install_append_class-target() to
do_install_append() in the file:
	meta/recipes-core/coreutils/coreutils_8.25.bb
in this way, the alternative system can find the files, the warnings
disappear.

(From OE-Core rev: 37039da6a09d7781beb93892932488940786b41f)

Signed-off-by: Dengke Du <dengke.du@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>