[MS demangler] Use a slightly shorter unmangling for mangled strings.

Before: const wchar_t * {L"%"}
Now: L"%"

See also PR39593.
Differential Revision: https://reviews.llvm.org/D54294


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@346544 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed