PR:		kern/8990
PR:		kern/8990

    If timer calculation results in degenerate value (0), force it to 1
    to avoid divide-by-zero panic later on in calls to IGMP_RANDOM_DELAY().
    I considered simply adding 1 to the timer calculation, but was unsure
    if the calculation was part of the IGMP standard or not so did not want
    to mess with it for all cases.

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