[cmake] Include the new file in the CMake lists. Without this every
CMake build of any part of LLVM with LLDB checked out fails immediately.
=[

We appear to not even have a build bot covering the CMake build of LLDB
which makes this truly terrible. That needs to be fixed immediately.

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@218831 91177308-0d34-0410-b5e6-96231b3b80d8