Emit symbol maps for compiled code for use by the Linux perf tool.

runtime/bin/process_linux.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "bin/process.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <poll.h>
 #include <signal.h>
@@ skipping 545 matching lines @@
   if (result == -1) {
     return false;
   }
   return true;
 }
 
 
 void Process::TerminateExitCodeHandler() {
   ExitCodeHandler::TerminateExitCodeThread();
 }
+
+
+intptr_t Process::CurrentProcessId() {
+  return static_cast<intptr_t>(getpid());
+}