Adding labeling for vendor security patch prop

This will allow adb shell getprop ro.vendor.build.security_patch to
properly return the correct build property, whereas previously it was
offlimits due to lack of label.

Test: adb shell getprop ro.vendor.build.security_patch successfully
returns whatever VENDOR_SECURITY_PATCH is defined to be in the Android
.mk files

Change-Id: Ie8427738125fc7f909ad8d51e4b76558f5544d49
diff --git a/private/compat/26.0/26.0.ignore.cil b/private/compat/26.0/26.0.ignore.cil
index cfda748..3e22734 100644
--- a/private/compat/26.0/26.0.ignore.cil
+++ b/private/compat/26.0/26.0.ignore.cil
@@ -112,6 +112,7 @@
     untrusted_app_all_devpts
     update_engine_log_data_file
     vendor_default_prop
+    vendor_security_patch_level_prop
     usbd
     usbd_exec
     usbd_tmpfs