AU: Mix stdout and stderr together in the logs.

BUG=none
TEST=Updated on tegra2_dev-board

Review URL: http://codereview.chromium.org/3398011

Change-Id: Ide2325f346e1858381da398c52659e53d0b20e44
diff --git a/subprocess.h b/subprocess.h
index 6685f4d..8f97c5d 100644
--- a/subprocess.h
+++ b/subprocess.h
@@ -63,6 +63,10 @@
   // requested callback.
   static void GChildExitedCallback(GPid pid, gint status, gpointer data);
 
+  // Callback which runs in the child before exec to redirect stderr onto
+  // stdout.
+  static void GRedirectStderrToStdout(gpointer user_data);
+
   struct SubprocessCallbackRecord {
     ExecCallback callback;
     void* callback_data;