Add the missing link between compiled code and the debugger.

When a debugger connects and disconnects, we now let compiled code know that we
need to be kept informed about what's going on.

Also fix a threading bug when threads exit with a debugger attached.

Also some minor tidying, mostly involving naming.

Change-Id: Iba0e8b9d192ac76ba1cd29a8b1e6d94f6f20dea8
diff --git a/src/dalvik_system_VMRuntime.cc b/src/dalvik_system_VMRuntime.cc
index ef11f4b..030caed 100644
--- a/src/dalvik_system_VMRuntime.cc
+++ b/src/dalvik_system_VMRuntime.cc
@@ -96,7 +96,7 @@
 }
 
 static jboolean VMRuntime_isDebuggerActive(JNIEnv*, jobject) {
-  return Dbg::IsDebuggerConnected();
+  return Dbg::IsDebuggerActive();
 }
 
 static jobjectArray VMRuntime_properties(JNIEnv* env, jobject) {
@@ -125,7 +125,6 @@
 }
 
 static void DisableCheckJniCallback(Thread* t, void*) {
-  LOG(INFO) << "Disabling CheckJNI for " << *t;
   t->GetJniEnv()->SetCheckJniEnabled(false);
 }