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/native_stack_dump.cc b/runtime/native_stack_dump.cc
index 7e16357..f166714 100644
--- a/runtime/native_stack_dump.cc
+++ b/runtime/native_stack_dump.cc
@@ -40,6 +40,7 @@
 #include "android-base/stringprintf.h"
 
 #include "arch/instruction_set.h"
+#include "base/file_utils.h"
 #include "base/memory_tool.h"
 #include "base/mutex.h"
 #include "base/unix_file/fd_file.h"