Merge branch 'sp/maint-fd-limit'

* sp/maint-fd-limit:
  sha1_file.c: Don't retain open fds on small packs
  mingw: add minimum getrlimit() compatibility stub
  Limit file descriptors used by packs

diff --cc cache.h
Simple merge

diff --cc compat/mingw.h
Simple merge

diff --cc fast-import.c
Simple merge

diff --cc sha1_file.c
Simple merge