New Issue: Set CHPL_LLVM=none for pre-merge travis builds

17135, “daviditen”, “Set CHPL_LLVM=none for pre-merge travis builds”, “2021-02-09T19:17:33Z”

The pre-merge travis builds are detecting a system LLVM in Enable LLVM by default by daviditen · Pull Request #17133 · chapel-lang/chapel · GitHub but then failing to build with it. Set CHPL_LLVM=none in those builds.