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/runtime/native/dalvik_system_VMRuntime.cc b/runtime/native/dalvik_system_VMRuntime.cc
index 6446e1b..400518d 100644
--- a/runtime/native/dalvik_system_VMRuntime.cc
+++ b/runtime/native/dalvik_system_VMRuntime.cc
@@ -32,8 +32,8 @@
 #include "class_linker-inl.h"
 #include "common_throws.h"
 #include "debugger.h"
-#include "dex_file-inl.h"
-#include "dex_file_types.h"
+#include "dex/dex_file-inl.h"
+#include "dex/dex_file_types.h"
 #include "gc/accounting/card_table-inl.h"
 #include "gc/allocator/dlmalloc.h"
 #include "gc/heap.h"