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/quick/arm64/call_arm64.cc b/compiler/dex/quick/arm64/call_arm64.cc
index 089e4b6..6492442 100644
--- a/compiler/dex/quick/arm64/call_arm64.cc
+++ b/compiler/dex/quick/arm64/call_arm64.cc
@@ -16,9 +16,13 @@
 
 /* This file contains codegen for the Thumb2 ISA. */
 
-#include "arm64_lir.h"
 #include "codegen_arm64.h"
+
+#include "arm64_lir.h"
+#include "base/logging.h"
+#include "dex/mir_graph.h"
 #include "dex/quick/mir_to_lir-inl.h"
+#include "driver/compiler_driver.h"
 #include "gc/accounting/card_table.h"
 #include "entrypoints/quick/quick_entrypoints.h"
 #include "mirror/art_method.h"