Ensure that a jar file is closed

On Windows we get into trouble if this jar file is left open.  Windows
refuses to delete an open file, which then causes post-test `@TempDir`
cleanup to fail.

core/src/test/java/com/ibm/wala/core/tests/shrike/FloatingPointsTest.java

@@ -150,16 +150,18 @@ public void emitTo(Output w) {
   }
 
   private void write() throws IllegalStateException, IOException, InvalidClassFileException {
-    // Write all modified classes
-    for (ClassInstrumenter ci2 : classInstrumenters) {
-      if (ci2.isChanged()) {
-        ClassWriter cw = ci2.emitClass();
-        instrumenter.outputModifiedClass(ci2, cw);
+    try {
+      // Write all modified classes
+      for (ClassInstrumenter ci2 : classInstrumenters) {
+        if (ci2.isChanged()) {
+          ClassWriter cw = ci2.emitClass();
+          instrumenter.outputModifiedClass(ci2, cw);
+        }
       }
+    } finally {
+      // Finally write the instrumented jar
+      instrumenter.close();
     }
-
-    // Finally write the instrumented jar
-    instrumenter.close();
   }
 
   private void setValidationInstrumenter() throws IOException {