8233855: [TESTBUG] appcds/FieldLayoutFlags.java failed to clean up files after test

Reviewed-by: hseigel

Author: iklam

test/hotspot/jtreg/runtime/cds/appcds/TestCommon.java

@@ -343,6 +343,7 @@ private static void patchJarForDynamicDump(String cp) throws Exception {
             newFile.renameTo(oldFile);
             System.out.println("firstJar = " + firstJar + " Modified");
         } else {
+            zipFile.close();
             System.out.println("firstJar = " + firstJar);
         }
     }