package.bbclass: add a stub implementation of package_name_hook

package.bbclass: add a stub implementation of package_name_hook

do_package() calls package_name_hook so that e.g. debian-style renaming through
debian.bbclass can happen.  If there is no class providing a package_name_hook
then this causes "WARNING: Function package_name_hook doesn't exist" every time
do_package() is executed.

Silence this warning by providing an empty package_name_hook in package.bbclass.

(From OE-Core rev: f6eb8e4e44b66217e4ada9f830a058c5ba120932)

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>