ART: Introduce thread-current-inl.h

Factor out Thread::Current() code into its own -inl file to remove
transitive includes.

This requires at the same time correcting mutex.h, i.e., moving
some functions into mutex-inl.h.

Test: m test-art-host
Change-Id: I88f888b604e0897368d9b483edce6ce4332dd9c9
diff --git a/runtime/openjdkjvmti/ti_monitor.cc b/runtime/openjdkjvmti/ti_monitor.cc
index 645faea..61bf533 100644
--- a/runtime/openjdkjvmti/ti_monitor.cc
+++ b/runtime/openjdkjvmti/ti_monitor.cc
@@ -39,7 +39,7 @@
 #include "art_jvmti.h"
 #include "runtime.h"
 #include "scoped_thread_state_change-inl.h"
-#include "thread-inl.h"
+#include "thread-current-inl.h"
 
 namespace openjdkjvmti {