ART: Some Quick cleanup

Make several fields const in CompilationUnit. May benefit some Mir2Lir
code that repeats tests, and in general immutability is good.

Remove compiler_internals.h and refactor some other headers to reduce
overly broad imports (and thus forced recompiles on changes).

Change-Id: I898405907c68923581373b5981d8a85d2e5d185a
diff --git a/compiler/dex/global_value_numbering.h b/compiler/dex/global_value_numbering.h
index d72144a..cdafc68 100644
--- a/compiler/dex/global_value_numbering.h
+++ b/compiler/dex/global_value_numbering.h
@@ -17,8 +17,11 @@
 #ifndef ART_COMPILER_DEX_GLOBAL_VALUE_NUMBERING_H_
 #define ART_COMPILER_DEX_GLOBAL_VALUE_NUMBERING_H_
 
+#include "base/logging.h"
 #include "base/macros.h"
-#include "compiler_internals.h"
+#include "mir_graph.h"
+#include "compiler_ir.h"
+#include "dex_flags.h"
 #include "utils/arena_object.h"
 
 namespace art {
@@ -252,7 +255,7 @@
 };
 std::ostream& operator<<(std::ostream& os, const GlobalValueNumbering::Mode& rhs);
 
-inline  void GlobalValueNumbering::StartPostProcessing() {
+inline void GlobalValueNumbering::StartPostProcessing() {
   DCHECK(Good());
   DCHECK_EQ(mode_, kModeGvn);
   mode_ = kModeGvnPostProcessing;