MS ABI: Fix mangling of static methods and function references

Function references always use $1? like function pointers and never $E?
like var decl references.  Static methods are mangled like function
pointers.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@200869 91177308-0d34-0410-b5e6-96231b3b80d8