Merge r343347 into the 7.0 branch : make lit builtins a package

|  |  |
| --- | --- |
| Bugzilla Link | [39117](https://llvm.org/bz39117) |
| Resolution | FIXED |
| Resolved on | Oct 19, 2018 10:50 |
| Version | 7.0 |
| OS | All |
| Blocks | llvm/llvm-project#38454  |
| Fixed by commit(s) | r343347 r344792 |

## Extended Description 
Is it OK to merge the following revision(s) to the 7.0 branch?