B09002 - killing monsters seen by infravision

B09002 - killing monsters seen by infravision
ohitmon was incorrectly using location visibility in a couple places where
monster visibility was more appropriate.  I'm still not sure about the
canspotmon check for destroy vs killed.  Similar checks do no appear
elsewhere in the code.  But at least now the 'destroyed' won't be shown
for a seen, living monster.