Version bump to QPR1.180521.001

Change-Id: Id4afc910fd8d1815462e9c5abdcb9abf8abf272f
diff --git a/core/build_id.mk b/core/build_id.mk
index f5f9b71..c94d72d 100644
--- a/core/build_id.mk
+++ b/core/build_id.mk
@@ -18,4 +18,4 @@
 # (like "CRB01").  It must be a single word, and is
 # capitalized by convention.
 
-BUILD_ID=QPR1.180520.001
+BUILD_ID=QPR1.180521.001