Implement most of VMStack and some of Zygote.

Change-Id: I07e18259a0452a2a9b077148f4f1ca67d3f63427
diff --git a/src/dalvik_system_VMRuntime.cc b/src/dalvik_system_VMRuntime.cc
index 1e95637..1bc1e39 100644
--- a/src/dalvik_system_VMRuntime.cc
+++ b/src/dalvik_system_VMRuntime.cc
@@ -88,7 +88,7 @@
 
 jboolean VMRuntime_isDebuggerActive(JNIEnv*, jobject) {
   // TODO: debugger!
-  return false;
+  return JNI_FALSE;
 }
 
 jobjectArray VMRuntime_properties(JNIEnv* env, jobject) {