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.

(From OE-Core rev: c269547ae8e90a78349f6003385137e4145e145f)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/insane.bbclass

@@ -681,15 +681,15 @@ python populate_lic_qa_checksum() {
     import tempfile
     sane = True
 
-    lic_files = d.getVar('LIC_FILES_CHKSUM', True)
+    lic_files = d.getVar('LIC_FILES_CHKSUM', True) or ''
     lic = d.getVar('LICENSE', True)
     pn = d.getVar('PN', True)
 
     if lic == "CLOSED":
         return
 
-    if not lic_files:
-        package_qa_handle_error("license-checksum", pn + ": Recipe file does not have license file information (LIC_FILES_CHKSUM)", d)
+    if not lic_files and d.getVar('SRC_URI', True):
+        package_qa_handle_error("license-checksum", pn + ": Recipe file fetches files and does not have license file information (LIC_FILES_CHKSUM)", d)
         return
 
     srcdir = d.getVar('S', True)