Create dex subdirectory

Move all the DexFile related source to a common subdirectory dex/ of
runtime.

Bug: 71361973
Test: make -j 50 test-art-host
Change-Id: I59e984ed660b93e0776556308be3d653722f5223
diff --git a/compiler/optimizing/block_builder.cc b/compiler/optimizing/block_builder.cc
index 0c92600..2b568bc 100644
--- a/compiler/optimizing/block_builder.cc
+++ b/compiler/optimizing/block_builder.cc
@@ -18,8 +18,8 @@
 
 #include "base/logging.h"  // FOR VLOG.
 #include "bytecode_utils.h"
-#include "code_item_accessors-inl.h"
-#include "dex_file_exception_helpers.h"
+#include "dex/code_item_accessors-inl.h"
+#include "dex/dex_file_exception_helpers.h"
 #include "quicken_info.h"
 
 namespace art {