Correct ABI list change wrongly advertised as being in the 7.0 release

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@345670 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/abi/CHANGELOG.TXT b/lib/abi/CHANGELOG.TXT
index cce6cba..eb63693 100644
--- a/lib/abi/CHANGELOG.TXT
+++ b/lib/abi/CHANGELOG.TXT
@@ -13,7 +13,7 @@
 New entries should be added directly below the "Version" header.
 
 -----------
-Version 7.0
+Version 8.0
 -----------
 
 * r345260 - Making libc++ build under -fvisibility=hidden
@@ -43,6 +43,9 @@
   Symbol removed: __ZNSt3__221__thread_specific_ptrINS_15__thread_structEE16__at_thread_exitEPv
   Symbol removed: __ZNSt3__119__start_std_streamsE
 
+-----------
+Version 7.0
+-----------
 
 * r338479 - Elementary string conversions for integral types