ART: Remove runtime.h file_utils.h (iwyu)

It is unnecessary. Fix up transitive includes.

Test: mmma art
Change-Id: Idf25e8df37a3924cc88b5a549b715e9206ca0757
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index 35b7707..333025e 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -37,6 +37,7 @@
 #include "art_method-inl.h"
 #include "base/arena_allocator.h"
 #include "base/casts.h"
+#include "base/file_utils.h"
 #include "base/leb128.h"
 #include "base/logging.h"
 #include "base/os.h"