classes/insane: do not force LIC_FILES_CHKSUM unless SRC_URI is set
Recipes such as images and packagegroups don't actually fetch or build
any source, so there's really no point having LIC_FILES_CHKSUM set.
Forcing users to set it (as we have done for images inheriting
image.bbclass) just makes things more difficult for the user for no
discernable benefit. The easiest way to adjust this check is simply to
skip it if SRC_URI is not set since this is a pretty good indicator that
no source is being pulled in.
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
