imagetest-qemu: Add test case for dmesg check in target

Add a test case for error log check with command dmesg in target. The
case introduces a new folder in target, "/opt/test", which holds test
scripts running in target.

Signed-off-by Jiajun Xu <jiajun.xu@intel.com>

meta/classes/imagetest-qemu.bbclass

@@ -133,9 +133,11 @@ python do_qemuimagetest() {
                 ret = 1
             elif m.group('noresult') == "1":
                 ret = 2
-            print line,
+            line = line.strip('\n')
+            bb.note(line)
         else:
-            print line,
+            line = line.strip('\n')
+            bb.note(line)
     f.close()
 
     if ret != 0: