core: map UnsignedLong to UInt32

Windows ARM64 is a LLP64 platform, which means that `unsigned long` is a
32-bit value.  This was already mapped properly for x86_64, but somehow
had missed ARM64.  This repairs that which is required for building the
standard library.

Author: compnerd

stdlib/public/core/CTypes.swift

@@ -28,7 +28,7 @@ public typealias CUnsignedShort = UInt16
 public typealias CUnsignedInt = UInt32
 
 /// The C 'unsigned long' type.
-#if os(Windows) && arch(x86_64)
+#if os(Windows) && (arch(x86_64) || arch(arm64))
 public typealias CUnsignedLong = UInt32
 #else
 public typealias CUnsignedLong = UInt