Merge branch 'jc/pack-objects-bigfile' into maint

* jc/pack-objects-bigfile:
  Teach core.bigfilethreashold to pack-objects

diff --cc Documentation/config.txt
Simple merge

diff --cc cache.h
Simple merge

diff --cc config.c
Simple merge

diff --cc environment.c
Simple merge

diff --cc fast-import.c
Simple merge