[lldb] move more things from python to cmake

Summary: Move the copy of six.py, lldb.py and macosx/heap

Reviewers: labath

Subscribers: mgorny, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D69016

llvm-svn: 375024
GitOrigin-RevId: 1d4a40751ff3552494f063306d3b2e1879d49230