Merge branch 'rs/refs-string-slice'

Avoid unnecessary temporary allocations while looking for matching refs inside refs API. By René Scharfe (3) and Junio C Hamano (1) * rs/refs-string-slice: refs: do not create ref_entry when searching refs: use strings directly in find_containing_dir() refs: convert parameter of create_dir_entry() to length-limited string refs: convert parameter of search_ref_dir() to length-limited string