android-5.1.1_r13 -> android-5.1.1_r18

Change-Id: Ic59a3ed9bc4bc4adc8656ae362a6d9d3a560d7a5
diff --git a/default.xml b/default.xml
index 0585479..8ff4271 100644
--- a/default.xml
+++ b/default.xml
@@ -4,7 +4,7 @@
   <remote  name="aosp"
            fetch="https://android.googlesource.com"
            review="android-review.googlesource.com"
-           revision="refs/tags/android-5.1.1_r13" />
+           revision="refs/tags/android-5.1.1_r18" />
 
   <remote  name="github"
            fetch=".."