qemu.cfg: Delete host-kernel.cfg and seprate the config to host-kernel folder.

Also add host-kernel-check.cfg to host-kernel folder. It only contains the config used
to filder host version. This file only used in control.kernel-version.

host-kernel.cfg will be auto created according to host-kernel-base.cfg and  host-kernel folder.

Whenever you add a new host type to host-kernel folder, please also add it to
 host-kernel-check.cfg. Or script could not filter out this host type.

Add rhel.6.4 and rhel.6.5 host config.

Signed-off-by: Feng Yang <fyang@redhat.com>