Update bugfix security string to October
(cherry picked from commit ba16193f1e503e26381f81ff7d95820b75bb2247)

Change-Id: I51b38f63e35c76470dc3c3c1ed3e818a0e6e5a9a
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index dff27df..d616177 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -114,7 +114,7 @@
     #  It must be of the form "YYYY-MM-DD" on production devices.
     #  It must match one of the Android Security Patch Level strings of the Public Security Bulletins.
     #  If there is no $PLATFORM_SECURITY_PATCH set, keep it empty.
-      PLATFORM_SECURITY_PATCH := 2017-09-01
+      PLATFORM_SECURITY_PATCH := 2017-10-01
 endif
 
 ifeq "" "$(PLATFORM_BASE_OS)"