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/debugger.h b/src/debugger.h
index 77c307c..6c50e9e 100644
--- a/src/debugger.h
+++ b/src/debugger.h
@@ -95,13 +95,12 @@
   static void Disconnected();
   static void Disposed();
 
-  /*
-   * Returns "true" if a debugger is connected.  Returns "false" if it's
-   * just DDM.
-   */
-  static bool IsDebuggerConnected();
+  // Returns true if we're actually debugging with a real debugger, false if it's
+  // just DDMS (or nothing at all).
+  static bool IsDebuggerActive();
 
-  static bool IsDebuggingEnabled();
+  // Returns true if we had -Xrunjdwp or -agentlib:jdwp= on the command line.
+  static bool IsJdwpConfigured();
 
   static bool IsDisposed();