sed: fix "sed CMD -i nonexistent_file". Closes 7484

function                                             old     new   delta
sed_main                                             643     676     +33

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
ntpd: calculate offset to jitter ratio before updating jitter

The offset to jitter ratio is now calculated before updating
jitter to make the test more sensitive.

function                                             old     new   delta
ntp_init                                             460     474     +14
update_local_clock                                   752     764     +12
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(add/remove: 0/0 grow/shrink: 2/0 up/down: 26/0)               Total: 26 bytes

Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>