classes/image: suppress log_check mechanism for warnings/errors logged through BitBake

If you printed a warning through bb.warn() / bbwarn or an error through
bb.error() / bberror, this was also being picked up by our log_check
mechanism that was designed to pick up warnings and errors printed by
other programs used during do_rootfs. This meant you saw not only the
warning or error itself, you saw it a second time through log_check,
which is a bit ugly. Use the just-added BB_TASK_LOGGER to access the
logger and add a handler that we can use to find out if any warning or
error we find in the logs is one we should ignore as it has already been
printed.

Fixes [YOCTO #8223].

(From OE-Core rev: fb37304d27857df3c53c0867e81fbc8899b48089)

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

meta/classes/image.bbclass

@@ -208,6 +208,14 @@ PACKAGE_EXCLUDE[type] = "list"
 fakeroot python do_rootfs () {
     from oe.rootfs import create_rootfs
     from oe.manifest import create_manifest
+    import logging
+
+    logger = d.getVar('BB_TASK_LOGGER', False)
+    if logger:
+        logcatcher = bb.utils.LogCatcher()
+        logger.addHandler(logcatcher)
+    else:
+        logcatcher = None
 
     # NOTE: if you add, remove or significantly refactor the stages of this
     # process then you should recalculate the weightings here. This is quite
@@ -255,7 +263,7 @@ fakeroot python do_rootfs () {
     progress_reporter.next_stage()
 
     # generate rootfs
-    create_rootfs(d, progress_reporter=progress_reporter)
+    create_rootfs(d, progress_reporter=progress_reporter, logcatcher=logcatcher)
 
     progress_reporter.finish()
 }