trace_processor: improve test framework and add kernel LMK tests

Change-Id: I099ccdc91bf62631126032b419bde94e1c9a7449
diff --git a/tools/diff_test_trace_processor.py b/tools/diff_test_trace_processor.py
index 037f4e7..d7329c6 100755
--- a/tools/diff_test_trace_processor.py
+++ b/tools/diff_test_trace_processor.py
@@ -54,6 +54,8 @@
     stripped = line.strip()
     if stripped.startswith('#'):
       continue
+    elif not stripped:
+      continue
 
     [trace_fname, query_fname, expected_fname] = stripped.split(' ')