Separate file utilities from utils.cc

Reduce the dependencies from utils.cc to arch/ subdirectories, etc.

Bug: 22322814
Test: make test-art-host
Change-Id: I4decd15ff4ec460735bfb58cebb1c6a1bf32b68f
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index ec210d0..139de2b 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -60,6 +60,7 @@
 #include "base/arena_allocator.h"
 #include "base/dumpable.h"
 #include "base/enums.h"
+#include "base/file_utils.h"
 #include "base/memory_tool.h"
 #include "base/stl_util.h"
 #include "base/systrace.h"