[Windows] Define generic arguments registers for Windows x64

Summary:
When evaluating expressions the generic arguments registers are required by ABI.
This patch defines them.

Reviewers: zturner, stella.stamenova, labath

Subscribers: aleksandr.urakov, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D53753

llvm-svn: 345385