Convicted prisoner had twice before been placed on suicide watch, then released from it; over three week period got into fight with another prisoner, acted distant, had abrasions on wrist, was unkempt, not eating, lost weight, slept poorly, stated he “needed help,” falsely accused cell mate of raping him; then committed suicide ten days later after asking for his cellmate to be removed; court holds even if prisoner should have been moved to suicide watch due to incidents during the three week period, there were no signs of suicidal behavior ten days later when he committed suici