ART: Add GetClassFields support

Add GetClassFields support. Add a test.

Bug: 31684578
Test: m test-art-host-run-test-912-classes
Change-Id: Id7509ef10ec9c19b54b7db8637729556b91273e5
diff --git a/test/912-classes/src/Main.java b/test/912-classes/src/Main.java
index a2dc7e1..a7f3b3f 100644
--- a/test/912-classes/src/Main.java
+++ b/test/912-classes/src/Main.java
@@ -43,6 +43,10 @@
     testClassType(int[].class);
     testClassType(Runnable[].class);
     testClassType(String[].class);
+
+    testClassFields(Integer.class);
+    testClassFields(int.class);
+    testClassFields(String[].class);
   }
 
   private static Class<?> proxyClass = null;
@@ -72,8 +76,14 @@
     System.out.println(c.getName() + " interface=" + isInterface + " array=" + isArray);
   }
 
+  private static void testClassFields(Class<?> c) throws Exception {
+    System.out.println(Arrays.toString(getClassFields(c)));
+  }
+
   private static native String[] getClassSignature(Class<?> c);
 
   private static native boolean isInterface(Class<?> c);
   private static native boolean isArrayClass(Class<?> c);
+
+  private static native Object[] getClassFields(Class<?> c);
 }