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.

(cherry picked from commit 9433ec60b325b708b9fa87e699ab4a6565741494)

Change-Id: I9ab03b1653e69f44cc98946dc89d764c3e045dd4
diff --git a/runtime/trace.cc b/runtime/trace.cc
index 29c01e4..2cc50b3 100644
--- a/runtime/trace.cc
+++ b/runtime/trace.cc
@@ -431,6 +431,15 @@
                                                     instrumentation::Instrumentation::kMethodExited |
                                                     instrumentation::Instrumentation::kMethodUnwind);
     }
+    if (the_trace->trace_file_.get() != nullptr) {
+      // Do not try to erase, so flush and close explicitly.
+      if (the_trace->trace_file_->Flush() != 0) {
+        PLOG(ERROR) << "Could not flush trace file.";
+      }
+      if (the_trace->trace_file_->Close() != 0) {
+        PLOG(ERROR) << "Could not close trace file.";
+      }
+    }
     delete the_trace;
   }
   runtime->GetThreadList()->ResumeAll();