This change also allows us to stop overriding argv[0] with the absolute
path of the executable, allowing us to preserve e.g. the case of the
executable's file name.
This fixes https://github.com/git-for-windows/git/issues/1496 partially.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>