[NFC] Add missing revision information to ABI Changelog

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@355732 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/abi/CHANGELOG.TXT b/lib/abi/CHANGELOG.TXT
index 60227e3..8055aba 100644
--- a/lib/abi/CHANGELOG.TXT
+++ b/lib/abi/CHANGELOG.TXT
@@ -16,7 +16,7 @@
 Version 9.0
 -----------
 
-* rTBD - Fix -fsanitize=vptr badness in <__debug>
+* r355367 - Fix -fsanitize=vptr badness in <__debug>
 
   This patch fixes a lifetime bug when inserting a new container into the debug database. It is
   diagnosed by UBSAN when debug mode is enabled. This patch corrects how nodes are constructed