Added regression test for throwing NullPointerException

Author: cristina-david

regression/cbmc-java/NullPointerException2/A.class

@@ -0,0 +1,18 @@
+class B extends RuntimeException {}
+
+class A {
+    int i;
+}
+
+public class Test {
+    public static void main(String args[]) {
+	A a=null;
+	try {
+	    int i=a.i;
+	    throw new B();
+	}
+	catch (NullPointerException exc) {
+	    assert false;
+	}
+    }
+}

regression/cbmc-java/NullPointerException2/B.class

@@ -0,0 +1,9 @@
+CORE
+Test.class
+--java-throw-runtime-exceptions
+^EXIT=10$
+^SIGNAL=0$
+^.*assertion at file Test.java line 15 function.*: FAILURE$
+^VERIFICATION FAILED$
+--
+^warning: ignoring