Merge branch 'nd/clone-connectivity-shortcut' (early part) into maint

Cloning with "git clone --depth N" while fetch.fsckobjects (or
transfer.fsckobjects) is set to true did not tell the cut-off points
of the shallow history to the process that validates the objects and
the history received, causing the validation to fail.

* 'nd/clone-connectivity-shortcut' (early part):
  fetch-pack: prepare updated shallow file before fetching the pack
  clone: let the user know when check_everything_connected is run
configure: fix option help message for --disable-pthreads

The configure option to disable threading is '--disable-pthreads',
not '--without-pthreads'.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git 1.8.3.2

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Sync with 1.8.3.2