Allow detaching of ownership of the argv_array's contents and add a
function to free those detached argv_arrays later.
This makes it possible to use argv_array efficiently with the exiting
struct child_process which only contains a member char **argv.
Add to documentation.
Signed-off-by: Florian Achleitner <florian.achleitner.2.6.31@gmail.com>
Acked-by: David Michael Barr <b@rr-dav.id.au>
Signed-off-by: Junio C Hamano <gitster@pobox.com>