This adds assembler / disassembler support for the decimal
floating-point instructions. Since LLVM does not yet have
support for decimal float types, these cannot be used for
codegen at this point.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304203 91177308-0d34-0410-b5e6-96231b3b80d8
