lit: Make sure the builtin_commands directory is packaged by setup.py
lit: Make sure the builtin_commands directory is packaged by setup.py

Summary: This directory was missing from the lit package on pypi.org.

Reviewers: ddunbar

Subscribers: delcypher, llvm-commits

Differential Revision: https://reviews.llvm.org/D51670

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@343115 91177308-0d34-0410-b5e6-96231b3b80d8

GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm