[MS Demangler] Demangle special operator 'dynamic initializer'.

This is encoded as __E and should print something like
"dynamic initializer for 'Foo'(void)"

This also adds support for dynamic atexit destructor, which is
basically identical but encoded as __F with slightly different
description.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@340239 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed