reviving units with full-heal can result in "missing for a week" notifications

[gondor2222]

If a unit is revived with full-heal and the body is never found (seems pretty easy to do if the body dies in an isolated place and is removed with the standard -r flag), the fort will still receive the notification after a week that that unit has been missing for a week. The notification can even be received multiple times if e.g. the unit is resurrected multiple times (occurred for me because I had to resurrect some units many times with a particularly nasty airborn+bloodborn+contagious+contact massive bleeding demon sickness syndrome

[myk002]

we can probably fix this by clearing the missing flag