fizzbuzz: Use an any+map combo to apply constraints

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
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fizzbuzz: Lift out the constraints into a var

Instead of hardcoding the constraints in match, lift them out to a
variable, and pass them in instead.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>