update SkJumper docs to Clang 5

We have been using Clang 5 since it was released,
starting with this CL: https://skia-review.googlesource.com/44241

Change-Id: I8167223d9fffc3bf065b6889097ad37648b069d3
Reviewed-on: https://skia-review.googlesource.com/76540
Reviewed-by: Yuqian Li <liyuqian@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
1 file changed