Update SMIMETest.java

Add identity and null checks before comparing byte arrays.

Author: cragkhit

util/src/test/java/org/bouncycastle/asn1/smime/test/SMIMETest.java

@@ -26,6 +26,14 @@ private boolean isSameAs(
         byte[]  a,
         byte[]  b)
     {
+        if (a == b)
+        {
+            return true;
+        }
+        if (null == a || null == b)
+        {
+            return false;
+        }
         if (a.length != b.length)
         {
             return false;