Portable refactorings.

Separate quick from portable entrypoints.
Move architectural dependencies into arch.

Change-Id: I9adbc0a9782e2959fdc3308215f01e3107632b7c
diff --git a/runtime/entrypoints/quick/quick_thread_entrypoints.cc b/runtime/entrypoints/quick/quick_thread_entrypoints.cc
index e711714..b4d6c0b 100644
--- a/runtime/entrypoints/quick/quick_thread_entrypoints.cc
+++ b/runtime/entrypoints/quick/quick_thread_entrypoints.cc
@@ -15,7 +15,7 @@
  */
 
 #include "callee_save_frame.h"
-#include "runtime_support.h"
+#include "entrypoints/entrypoint_utils.h"
 #include "thread.h"
 #include "thread_list.h"