Fix TestAttachDenied and TestChangeProcessGroup for remote Windows to Android.

Summary: Updated `append_to_remote_wd` to work for both remote and local.

Reviewers: clayborg, ovyalov

Reviewed By: ovyalov

Subscribers: tberghammer, lldb-commits

Differential Revision: http://reviews.llvm.org/D10288

llvm-svn: 239203