Clean up leftover lock file during upstart post-stop.

BUG=None
TEST=Verified the following on daisy with a WiMAX module:

  stop wimax_manager
  start wimax_manager
  restart wimax_manager

Change-Id: I3db383a7d35d48a21ecc4fe9460e51f1f2a204b8
Reviewed-on: https://chromium-review.googlesource.com/177154
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Ben Chan <benchan@chromium.org>
Tested-by: Ben Chan <benchan@chromium.org>
diff --git a/wimax_manager.conf b/wimax_manager.conf
index f27c6e4..714c769 100644
--- a/wimax_manager.conf
+++ b/wimax_manager.conf
@@ -18,6 +18,11 @@
   rm -rf /var/lock/gct
 end script
 
+post-stop script
+  # Clean up any leftover lock file.
+  rm -rf /var/lock/gct
+end script
+
 respawn
 expect fork