checkout: name check_linked_checkouts() more meaningfully
check_linked_checkouts() doesn't just "check" linked checkouts for
"something"; specifically, it aborts the operation if the branch about
to be checked out is already checked out elsewhere. Therefore, rename it
to die_if_checked_out() to give a better indication of its function.
The more meaningful name will be particularly important when this
function is later published for use by other callers.
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>