[libunwind] Remove the remote unwinding support

This is unfinished, unused and incomplete. This could be brought back in
the future if there's a desire to build a more complete implementation,
but at the moment it's just bitrotting.

Differential Revision: https://reviews.llvm.org/D57252

git-svn-id: https://llvm.org/svn/llvm-project/libunwind/trunk@352965 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed