Code clean-up around a much-less-important-than-it-used-to-be
update_server_info() funtion.

* jk/server-info-rabbit-hole:
  update_info_refs(): drop unused force parameter
  server-info: drop objdirlen pointer arithmetic
  server-info: drop nr_alloc struct member
  server-info: use strbuf to read old info/packs file
  server-info: simplify cleanup in parse_pack_def()
  server-info: fix blind pointer arithmetic
  http: simplify parsing of remote objects/info/packs
  packfile: fix pack basename computation
  midx: check both pack and index names for containment
  t5319: drop useless --buffer from cat-file
  t5319: fix bogus cat-file argument
  pack-revindex: open index if necessary
  packfile.h: drop extern from function declarations