Move casts.h and stl_util.h into base/.

Change-Id: Idb3bfa5cec3d146e488031d91265737cde2b4cf4
diff --git a/src/oat/utils/mips/assembler_mips.cc b/src/oat/utils/mips/assembler_mips.cc
index be1aceb..25ba9b2 100644
--- a/src/oat/utils/mips/assembler_mips.cc
+++ b/src/oat/utils/mips/assembler_mips.cc
@@ -16,7 +16,7 @@
 
 #include "assembler_mips.h"
 
-#include "casts.h"
+#include "base/casts.h"
 #include "memory_region.h"
 #include "oat/runtime/oat_support_entrypoints.h"
 #include "thread.h"
diff --git a/src/oat/utils/x86/assembler_x86.cc b/src/oat/utils/x86/assembler_x86.cc
index 010318b..fd8f152 100644
--- a/src/oat/utils/x86/assembler_x86.cc
+++ b/src/oat/utils/x86/assembler_x86.cc
@@ -16,7 +16,7 @@
 
 #include "assembler_x86.h"
 
-#include "casts.h"
+#include "base/casts.h"
 #include "memory_region.h"
 #include "oat/runtime/oat_support_entrypoints.h"
 #include "thread.h"