Replace NULL with nullptr

Also fixed some lines that were too long, and a few other minor
details.

Change-Id: I6efba5fb6e03eb5d0a300fddb2a75bf8e2f175cb
diff --git a/runtime/jdwp/jdwp.h b/runtime/jdwp/jdwp.h
index 8dffee6..55441c9 100644
--- a/runtime/jdwp/jdwp.h
+++ b/runtime/jdwp/jdwp.h
@@ -127,7 +127,7 @@
    * Among other things, this binds to a port to listen for a connection from
    * the debugger.
    *
-   * Returns a newly-allocated JdwpState struct on success, or NULL on failure.
+   * Returns a newly-allocated JdwpState struct on success, or nullptr on failure.
    */
   static JdwpState* Create(const JdwpOptions* options)
       LOCKS_EXCLUDED(Locks::mutator_lock_);