In MDStringArray() don't call MD5Update() on empty elements of array. This

doesn't change checksum, but could cause memory copy to be called with
zero length and/or NULL source/destination.

Sponsored by:   Sippy Software, Inc.
Debugging:      mpatrol

md5utils.c

@@ -78,7 +78,8 @@ void MDStringArray (char *dst, str src[], int size)
 		fprintf(stderr, " [%d]\n", sum );	
 #		endif
 */
-  		MDUpdate (&context, s, len);
+		if (len > 0)
+  			MDUpdate (&context, s, len);
   }
   MDFinal (digest, &context);