buildstats: Fix tracebacks for early task failures

If a failure occurs early in the task, its possible we can have a
TaskFailed before the TaskStarted event can be triggered. This in
turn causes another traceback as the directory buildstats writes
files into doesn't exist.

Ensure the directory exists so we can see the original error.

(From OE-Core rev: bd0a65ec47ebf55c549c9ef276b201b72396ce2b)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/buildstats.bbclass

@@ -167,6 +167,8 @@ python run_buildstats () {
                 f.write("Uncompressed Rootfs size: %s" % rootfs_size)
 
     elif isinstance(e, bb.build.TaskFailed):
+        # Can have a failure before TaskStarted so need to mkdir here too
+        bb.utils.mkdirhier(taskdir)
         write_task_data("failed", os.path.join(taskdir, e.task), e, d)
         ########################################################################
         # Lets make things easier and tell people where the build failed in