Move ROOTFS_POSTPROCESS_COMMANDs from core-image.bbclass to
image.bbclass so that images built using just image.bbclass
will benefit from them. Without this change, an image built
using image.bbclass did not honor read-only-rootfs image feature.
Signed-off-by: Gary Thomas <gary@mlbassoc.com> Signed-off-by: Ross Burton <ross.burton@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
