Merge branch 'jh/add-index-entry-optim'

"git checkout" that handles a lot of paths has been optimized by reducing the number of unnecessary checks of paths in the has_dir_name() function. * jh/add-index-entry-optim: read-cache: speed up has_dir_name (part 2) read-cache: speed up has_dir_name (part 1) read-cache: speed up add_index_entry during checkout p0006-read-tree-checkout: perf test to time read-tree read-cache: add strcmp_offset function