Update benchmark/single-source/BufferFill.swift

Co-authored-by: Karoy Lorentey <[email protected]>

Author: glessard

benchmark/single-source/BufferFill.swift

@@ -131,7 +131,9 @@ var b8: UnsafeMutableBufferPointer<UInt8> = .init(start: nil, count: 0)
 public func rawBufferCopyContentsSetup() {
   assert(r8.baseAddress == nil)
   let count = a.count * MemoryLayout<Int>.stride
-  let rb = UnsafeMutableRawBufferPointer.allocate(byteCount: count, alignment: 8)
+  let rb = UnsafeMutableRawBufferPointer.allocate(
+    byteCount: count, 
+    alignment: MemoryLayout<Int>.alignment)
   a.withUnsafeBytes {
     rb.copyMemory(from: $0)
   }