qemu.bbclass: add -r ${OLDEST_KERNEL} parameter

qemu.bbclass: add -r ${OLDEST_KERNEL} parameter

* in some cases (e.g. with external toolchain which doesn't respect our
  reasonably old version set in OLDEST_KERNEL) it's possible to have libc
  which requires newer kernel than what we have on builders, qemu supports
  -r param to use different uname than what's returned by host system.
* change qemu_run_binary to pass -r ${OLDEST_KERNEL} and add the same to
  QEMU_OPTIONS which are used by qemuwrapper-cross
* maybe we should eventually convert all qemu_run_binary usages always include
  qemuwrapper-cross dependency and always call qemu through that (it
  seems very strange that qemu_target_binary is called from qemuwrapper
  and for allarch recipes it can return qemu-allarch as qemu binary).

  qemu_run_binary is used by:
  meta/classes/gtk-immodules-cache.bbclass:            ${@qemu_run_binary(d, '$D', '${bindir}/gtk-query-immodules-$maj_ver.0')} \
  meta/classes/qemu.bbclass:def qemu_run_binary(data, rootfs_path, binary):
  meta/recipes-core/systemd/systemd_213.bb:         ${@qemu_run_binary(d, '$D', '${base_bindir}/udevadm')} hwdb --update \
  meta/recipes-graphics/pango/pango.inc:    ${@qemu_run_binary(d, '$D','${bindir}/${MLPREFIX}pango-querymodules')} \

  and qemuwrapper directly by:
  scripts/postinst-intercepts/update_font_cache:PSEUDO_UNLOAD=1 qemuwrapper -L $D -E LD_LIBRARY_PATH=$D/${libdir}:$D/${base_libdir}\
  scripts/postinst-intercepts/update_pixbuf_cache:PSEUDO_UNLOAD=1 qemuwrapper -L $D -E LD_LIBRARY_PATH=$D/${libdir}:$D/${base_libdir}\

(From OE-Core rev: 1f0bff320077f4d9f2ee51096a1438e8cae9dd0d)

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