ART: More header cleanup - runtime.h

Remove unnecessary runtime.h includes. Refactor other headers
(move to forward declarations) to make this possible.

Test: mmma art
Change-Id: I297f0ad444ba92169edd16d8c7cbe95bb6dbb800
diff --git a/runtime/verifier/method_verifier.h b/runtime/verifier/method_verifier.h
index b34a3af..9ef98f7 100644
--- a/runtime/verifier/method_verifier.h
+++ b/runtime/verifier/method_verifier.h
@@ -37,12 +37,17 @@
 
 namespace art {
 
+class ClassLinker;
 class CompilerCallbacks;
 class Instruction;
 struct ReferenceMap2Visitor;
 class Thread;
 class VariableIndentationOutputStream;
 
+namespace mirror {
+class DexCache;
+}  // namespace mirror
+
 namespace verifier {
 
 class MethodVerifier;