JCE: return defensive copy of IV in engineGetIV to prevent internal state mutation

Author: cconlon

src/main/java/com/wolfssl/provider/jce/WolfCryptCipher.java

@@ -697,7 +697,11 @@ else if (paddingType == PaddingType.WC_PKCS5) {
 
     @Override
     protected byte[] engineGetIV() {
-        return this.iv;
+        if (this.iv != null) {
+            return this.iv.clone();
+        }
+
+        return null;
     }
 
     @Override