set_m_flag
dot = set_m_flag(*ip, ~(MPRESERVE | MTOUCH), MTOUCH);
dot = set_m_flag(*ip,
mp = set_m_flag(*ip,
dot = set_m_flag(*ip, ~MDELETED, 0);
dot = set_m_flag(*ip, ~(MBOX | MPRESERVE), MPRESERVE);
dot = set_m_flag(*ip, ~(MREAD | MTOUCH | MSTATUS), MSTATUS);
dot = set_m_flag(*ip,
struct message *set_m_flag(int, int, int);
(void)set_m_flag(*ip, and_bits, xor_bits);