Empty commit at end of history preceding clang-format-6.0 style transition
This is an empty commit that precedes an automatic application of clang-format-6.0 to update the C++ style of our entire source tree. This may be helpful to rebase a topic branch that was originally based on a commit preceding the transition. One may first rebase the topic on this commit. Then use one of the following approaches. * Rewrite the topic, including this commit, using `git filter-branch` `--tree-filter` with `clang-format.bash` to update the style in every commit. Rebase the revised topic, excluding the rewrite of this commit, on the style transition commit. OR * Add a `.git/info/grafts` entry to change the parent of the first commit in the topic from this commit to the style transition commit. Rewrite the topic using `git filter-branch --tree-filter` with `clang-format.bash` to update the style in every commit. Then remove the graft, which was resolved by the filter. See `git help filter-branch` and `git help repository-layout` for details.