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/compiler/jni/quick/calling_convention.h b/compiler/jni/quick/calling_convention.h
index e256ce6..77a5d59 100644
--- a/compiler/jni/quick/calling_convention.h
+++ b/compiler/jni/quick/calling_convention.h
@@ -27,6 +27,8 @@
 
 namespace art {
 
+enum class InstructionSet;
+
 // Top-level abstraction for different calling conventions.
 class CallingConvention : public DeletableArenaObject<kArenaAllocCallingConvention> {
  public: