Wizard mode ^E and any mode spell of detect unseen or wand of secret
door detection failed to find mon->mundetected monsters if they were
hiding under objects, and failed to find those or other hiders or
mimics when the hidden monster was at a trap location. The fix for
the latter initially only worked if the trap was known, so took two
tries when a monster hid at the location of an unseen trap. So this
makes the additional change to find both things at the same time; it
isn't manual searching that stops as soon as something is found.