Squashed 'runtime/mruby/' content from commit b4cc962

git-subtree-dir: runtime/mruby
git-subtree-split: b4cc962c3a8bf13a108f2ba4fb07beb962ddede1
Merge commit '6e9f3fd50d5c77e676f8b8d866e95471d06f6094' as 'runtime/mruby'