Add missing comment for mangling.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@165202 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ItaniumMangle.cpp b/lib/AST/ItaniumMangle.cpp
index d8c6594..851944a 100644
--- a/lib/AST/ItaniumMangle.cpp
+++ b/lib/AST/ItaniumMangle.cpp
@@ -2095,6 +2095,7 @@
 //                         ::= Dv [<dimension expression>] _ <element type>
 // <extended element type> ::= <element type>
 //                         ::= p # AltiVec vector pixel
+//                         ::= b # Altivec vector bool
 void CXXNameMangler::mangleType(const VectorType *T) {
   if ((T->getVectorKind() == VectorType::NeonVector ||
        T->getVectorKind() == VectorType::NeonPolyVector)) {