[demangler] Add a partial demangling API for LLDB.

This parses a mangled name into an AST (typically an intermediate stage in
itaniumDemangle) and provides some functions to query certain properties or
print certain parts of the demangled name.

Differential revision: https://reviews.llvm.org/D44668

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@329951 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed