Tasknames can now start with "multiconfig:" which broke the virtual: comparison code and
lead to unpredictable checksums with nativesdk recipes. This adds in handling for
the new additional prefix which unbreaks nativesdk builds when using multiconfig.
(Bitbake rev: 0ca6b8438624d892ee7ef3b42df0024604b64567)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>