SHOULD_NOT_SLEEP and SHOULD_BE_PURE have false positives based on incorrect inheritance assumptions

[out-of-phaze]

/proc/foo()
    SHOULD_NOT_SLEEP(TRUE)

/datum/proc/foo()
    sleep(5)

/datum/proc/foo() will report that it has SHOULD_NOT_SLEEP set when it shouldn't.

[out-of-phaze]

An example in a real environment, although the proc didn't originally have the annotation--it was added for demonstration.