Use llvm3.9 on fedora rawhide, llvm4.0 was dropped.
Use llvm3.9 on fedora rawhide, llvm4.0 was dropped.

vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa