Version bump to OPR1.170531.002

Change-Id: I900abde4a1b4b0618c65e578129e87194f0d67d1
diff --git a/core/build_id.mk b/core/build_id.mk
index 2dd5262..e5278b6 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.
 
-export BUILD_ID=OPR1.170531.001
+export BUILD_ID=OPR1.170531.002