Make change and version bump to RP1A.191031.001

Change-Id: Ib0b9283776b1cbf69ed3b4edaa50b501aa3cfd6f
diff --git a/core/build_id.mk b/core/build_id.mk
index 2f9c3f3..3ff4c06 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=MASTER
+BUILD_ID=RP1A.191031.001