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_VMDebug.cc b/src/dalvik_system_VMDebug.cc
index 76750d7..f125272 100644
--- a/src/dalvik_system_VMDebug.cc
+++ b/src/dalvik_system_VMDebug.cc
@@ -104,11 +104,11 @@
 }
 
 static jboolean VMDebug_isDebuggerConnected(JNIEnv*, jclass) {
-  return Dbg::IsDebuggerConnected();
+  return Dbg::IsDebuggerActive();
 }
 
 static jboolean VMDebug_isDebuggingEnabled(JNIEnv*, jclass) {
-  return Dbg::IsDebuggingEnabled();
+  return Dbg::IsJdwpConfigured();
 }
 
 static jlong VMDebug_lastDebuggerActivity(JNIEnv*, jclass) {