Version bump to PPR1.171220.006

Change-Id: I67a7fd86b6aa6eebde6be5dd86521946effdd5f6
diff --git a/core/build_id.mk b/core/build_id.mk
index 58ac653..e91fd7f 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=PPR1.171220.005
+export BUILD_ID=PPR1.171220.006