ART: Track Flush & Close in FdFile

Implement a check that aborts when a file hasn't been explicitly
flushed and closed when it is destructed.

Add WARN_UNUSED to FdFile methods.

Update dex2oat, patchoat, scoped_flock and some gtests to pass with
this.

Change-Id: I9ab03b1653e69f44cc98946dc89d764c3e045dd4
diff --git a/runtime/Android.mk b/runtime/Android.mk
index 17ee8ab..0f5050b 100644
--- a/runtime/Android.mk
+++ b/runtime/Android.mk
@@ -295,6 +295,7 @@
   arch/x86_64/registers_x86_64.h \
   base/allocator.h \
   base/mutex.h \
+  base/unix_file/fd_file.h \
   dex_file.h \
   dex_instruction.h \
   gc/collector/gc_type.h \