GRH70B = GRH70 + NPE fixes in Maps.apk

Change-Id: I1c27cf39a1031d905faffa2ec14f0a1cffd2c19f
diff --git a/core/build_id.mk b/core/build_id.mk
index d0cf238..0fc8a30 100644
--- a/core/build_id.mk
+++ b/core/build_id.mk
@@ -19,4 +19,4 @@
 # (like "CRB01").  It must be a single word, and is
 # capitalized by convention.
 
-export BUILD_ID=GRH70
+export BUILD_ID=GRH70B