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

runtime/bin/process_win.cc

Index: runtime/bin/process_win.cc
diff --git a/runtime/bin/process_win.cc b/runtime/bin/process_win.cc
index f1081d57e56c90d605df9cd0cbbfad36d660ee73..ca4d1473f0d0c0a14f41160503c6d4c12d43f0b8 100644
--- a/runtime/bin/process_win.cc
+++ b/runtime/bin/process_win.cc
@@ -521,3 +521,8 @@ bool Process::Kill(intptr_t id, int signal) {
 void Process::TerminateExitCodeHandler() {
   // Nothing needs to be done on Windows.
 }
+
+
+intptr_t Process::CurrentProcessId() {
+  return static_cast<intptr_t>(GetCurrentProcessId());
+}