tools: Add new "test" taint to kernel-chktaint

Commit c272612cb4a2 ("kunit: Taint the kernel when KUnit tests are run")
added a new taint flag for when in-kernel tests run. This commit adds
recognition of this new flag in kernel-chktaint.

With this change the correct reason will be reported if the kernel is
tainted because of a test run.
Amended Commit log: Shuah Khan <[e-mail]>

Reviewed-by: David Gow <[e-mail]>
Signed-off-by: Joe Fradley <[e-mail]>
Reviewed-by: Brendan Higgins <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/debugging/kernel-chktaint

···
 	echo " * auxiliary taint, defined for and used by distros (#16)"
 
 fi
+
 T=`expr $T / 2`
 if [ `expr $T % 2` -eq 0 ]; then
 	addout " "
 else
 	addout "T"
 	echo " * kernel was built with the struct randomization plugin (#17)"
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+	addout " "
+else
+	addout "N"
+	echo " * an in-kernel test (such as a KUnit test) has been run (#18)"
 fi
 
 echo "For a more detailed explanation of the various taint flags see"