populate_sdk_ext: Change lockedsigs task mismatch to a warning

It has been determined that it is highly likely that users might get
signatures that don't match in an extensible sdk. This doesn't
necessarily happen with oe-core, so we can set the mismatch to an error
during testing if we like.

However, for the case where users are creating their own sdks, we don't
need an error halting their progress. locked-sigs will still function as
it should.

(From OE-Core rev: 6ba86d847275126bf435f144e7d029d10e7ab17d)

Signed-off-by: Randy Witt <randy.e.witt@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/populate_sdk_ext.bbclass

@@ -221,7 +221,7 @@ python copy_buildsystem () {
 
             # Error if the sigs in the locked-signature file don't match
             # the sig computed from the metadata.
-            f.write('SIGGEN_LOCKEDSIGS_TASKSIG_CHECK = "error"\n\n')
+            f.write('SIGGEN_LOCKEDSIGS_TASKSIG_CHECK = "warn"\n\n')
 
             # Hide the config information from bitbake output (since it's fixed within the SDK)
             f.write('BUILDCFG_HEADER = ""\n')