Fixes return value type in JNI method

Java_com_sun_java_util_jar_pack_NativeUnpack_getUnusedInput expects a
return value of type jobject. One line in the method was returning
false. Some compilers do not accept this so it has been changed to
return null instead.

Signed-off-by: jimmyk <jimmyk@ca.ibm.com>

jdk/src/share/native/com/sun/java/util/jar/pack/jni.cpp

@@ -22,6 +22,13 @@
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
+
+/*
+ * ===========================================================================
+ * (c) Copyright IBM Corp. 2024, 2024 All Rights Reserved
+ * ===========================================================================
+ */
+
 #include <sys/types.h>
 
 #include <stdio.h>
@@ -292,7 +299,7 @@ Java_com_sun_java_util_jar_pack_NativeUnpack_getUnusedInput(JNIEnv *env, jobject
 
  if (uPtr->aborting()) {
  THROW_IOE(uPtr->get_abort_message());
- return false;
+ return null;
  }
 
  // We have fetched all the files.