[BinaryFormat] Add MsgPackTypes

Add data structure to represent MessagePack "documents" and convert
to/from both MessagePack and YAML encodings.

Differential Revision: https://reviews.llvm.org/D48175

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@346978 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed