F-15064: correct AesGcm mallocNativeStruct() Javadoc to say allocation happens on first use

src/main/java/com/wolfssl/wolfcrypt/AesGcm.java

@@ -107,8 +107,8 @@ public class AesGcm extends NativeStruct {
     }
 
     /**
-     * Malloc native Aes structure via JNI. Called by NativeStruct
-     * constructor when this object is created.
+     * Malloc native Aes structure via JNI. Called by initNativeStruct()
+     * on first use of this object.
      *
      * @return native allocated pointer
      *