ART: Remove instruction_set.h from thread.h

Move the function definitions relying on it to the -inl. Some
follow-up transitive-include cleanup, as well as some more
forward-declarations.

Bug: 119869270
Test: mmma art
Change-Id: I820f395e6cb8343a4bb9bf02da271fbec067109f
diff --git a/runtime/runtime.h b/runtime/runtime.h
index a2d519d..a249c9f 100644
--- a/runtime/runtime.h
+++ b/runtime/runtime.h
@@ -27,7 +27,6 @@
 #include <memory>
 #include <vector>
 
-#include "arch/instruction_set.h"
 #include "base/locks.h"
 #include "base/macros.h"
 #include "base/mem_map.h"
@@ -84,6 +83,7 @@
 class ClassLinker;
 class CompilerCallbacks;
 class DexFile;
+enum class InstructionSet;
 class InternTable;
 class IsMarkedVisitor;
 class JavaVMExt;