[benchmark] Fix silly thinkos in Ackermann & Fibonacci

Author: lorentey

benchmark/single-source/Ackermann.swift

@@ -23,8 +23,8 @@ public let benchmarks = [
 
 func _ackermann(_ m: Int, _ n : Int) -> Int {
   if (m == 0) { return n + 1 }
-  if (n == 0) { return ackermann(m - 1, 1) }
-  return ackermann(m - 1, ackermann(m, n - 1))
+  if (n == 0) { return _ackermann(m - 1, 1) }
+  return _ackermann(m - 1, _ackermann(m, n - 1))
 }
 
 @inline(never)

benchmark/single-source/Fibonacci.swift

@@ -21,7 +21,7 @@ public let benchmarks = [
 
 func _fibonacci(_ n: Int) -> Int {
   if (n <= 2) { return 1 }
-  return fibonacci(n - 2) + fibonacci(n - 1)
+  return _fibonacci(n - 2) + _fibonacci(n - 1)
 }
 
 @inline(never)