Update microsoftDemangle() to work more like itaniumDemangle().

* Use same method of initializing the output stream and its buffer
* Allow a nullptr Status pointer
* Don't print the mangled name on demangling error
* Write to N (if it is non-nullptr)

Differential Revision: https://reviews.llvm.org/D52104


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@342330 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed