ART: Some runtime cleanup

Use an enum for the compiler-callback mode.

Refactor and remove some unnecessary includes in runtime.h.

Change-Id: If2245fa470171311b8e05b677cf6bb28f209585a
diff --git a/compiler/common_compiler_test.cc b/compiler/common_compiler_test.cc
index d506cc2..257406a 100644
--- a/compiler/common_compiler_test.cc
+++ b/compiler/common_compiler_test.cc
@@ -179,7 +179,7 @@
   method_inliner_map_.reset(new DexFileToMethodInlinerMap);
   callbacks_.reset(new QuickCompilerCallbacks(verification_results_.get(),
                                               method_inliner_map_.get(),
-                                              false));
+                                              CompilerCallbacks::CallbackMode::kCompileApp));
   options->push_back(std::make_pair("compilercallbacks", callbacks_.get()));
 }