Expand statistics feature to cover all vm stats

Block access to the choice point stack and trail stats
unless the statistics feature is enabled for the VM.

Change-Id: Ifb7baa1ddc1605c3324e0c1f5f802b1daf2b6f05

src/builtin/PRED_$statistics_2.java

diff --git a/src/builtin/PRED_$statistics_2.java b/src/builtin/PRED_$statistics_2.java
index 6d8b75c..e77864e 100644
--- a/src/builtin/PRED_$statistics_2.java
+++ b/src/builtin/PRED_$statistics_2.java
@@ -28,12 +28,12 @@
 	Term result = null;
 
 	a1 = a1.dereference();
+    engine.requireFeature(Prolog.Feature.STATISTICS, this, a1);
 	if (a1.isVariable()) {
 	    throw new PInstantiationException(this, 1);
 	} else if (! a1.isSymbol()) {
 	    throw new IllegalTypeException(this, 1, "atom", a1);
 	} else if (a1.equals(SYM_RUNTIME)) {
-	    engine.requireFeature(Prolog.Feature.STATISTICS_RUNTIME, this, a1);
 	    long val1, val2;
 	    Term start, previous;
 	    val1 = System.currentTimeMillis() - engine.getStartRuntime();
@@ -61,7 +61,7 @@
 	} else {
 	    return engine.fail();
 	}
-	if (! a2.unify(result, engine.trail)) 
+	if (! a2.unify(result, engine.trail))
 	    return engine.fail();
 	return cont;
     }

src/lang/Prolog.java

diff --git a/src/lang/Prolog.java b/src/lang/Prolog.java
index 231ab2c..205f71d 100644
--- a/src/lang/Prolog.java
+++ b/src/lang/Prolog.java
@@ -90,7 +90,7 @@
       IO,
 
       /** Track the running time of evaluations */
-      STATISTICS_RUNTIME;
+      STATISTICS;
     }
     protected final EnumSet<Feature> features = EnumSet.noneOf(Feature.class);
 
@@ -149,7 +149,7 @@
 	halt = 0;
 	debug = "off";
 	exception = NONE;
-	startRuntime = features.contains(Feature.STATISTICS_RUNTIME)
+	startRuntime = features.contains(Feature.STATISTICS)
 	    ? System.currentTimeMillis()
 	    : 0;
 	previousRuntime = 0;