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/dex2oat/dex2oat.cc b/dex2oat/dex2oat.cc
index f1cd30a..2e1b7ae 100644
--- a/dex2oat/dex2oat.cc
+++ b/dex2oat/dex2oat.cc
@@ -1053,9 +1053,12 @@
     }
 
     verification_results_.reset(new VerificationResults(compiler_options_.get()));
-    callbacks_.reset(new QuickCompilerCallbacks(verification_results_.get(),
-                                                &method_inliner_map_,
-                                                image_));
+    callbacks_.reset(new QuickCompilerCallbacks(
+        verification_results_.get(),
+        &method_inliner_map_,
+        image_ ?
+            CompilerCallbacks::CallbackMode::kCompileBootImage :
+            CompilerCallbacks::CallbackMode::kCompileApp));
     runtime_options.push_back(std::make_pair("compilercallbacks", callbacks_.get()));
     runtime_options.push_back(
         std::make_pair("imageinstructionset", GetInstructionSetString(instruction_set_)));