It will be exiled. The fact that it was cycled is an information about the card before it became a spell on the stack; the zone changes it undergoes make it a new object that Sarcophagus won't track as having been cycled.
EDIT : However, note that if you cycle Ichor Slick but don't cast it with Madness, the fact that it goes through the exile zone before going to the graveyard doesn't stop Sarcophagus from tracking it as having been cycled, thanks to this particular rule:
702.34c. After resolving a madness triggered ability, if the exiled card wasn't cast and was moved to a public zone, effects referencing the discarded card can find that card. See rule 400.7i.
So the Sarcophagus will let it go to the graveyard in that case.
I'm a former judge (lapsed), who keeps up to date on rules and policy. Keep in mind that judges' answers aren't necessarily more valid than those of people who aren't judges; what matters is we can quote the rules to back up our answers. When in doubt, ask for such quotes.
It will be exiled. If you don't cast it it will go to the graveyard as normal.
Note, that there is this a very recent change to the rules regarding madness. So the two answers don't contradict.
400.7. An object that moves from one zone to another becomes a new object with no memory of, or
relation to, its previous existence. There are nine exceptions to this rule:
[...]
400.7i After resolving a madness triggered ability (see rule 702.34), if the exiled card wasn’t cast
and was moved to a public zone, effects referencing the discarded card can find that object.
EDIT : However, note that if you cycle Ichor Slick but don't cast it with Madness, the fact that it goes through the exile zone before going to the graveyard doesn't stop Sarcophagus from tracking it as having been cycled, thanks to this particular rule: So the Sarcophagus will let it go to the graveyard in that case.
Note, that there is this a very recent change to the rules regarding madness. So the two answers don't contradict.
Former Rules Advisor
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(The Gamers: Dorkness Rising)
"Any sufficiently analyzed magic is indistinguishable from science."
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