Foundation: adjust NSTemporaryDirectory for Windows

Windows provides `GetTempPath` for getting the temporary directory which
consults the environment variables and falls back through a cascading
set ultimately ending up at `%SystemRoot%\Temp` if nothing else is
found.  The last path is not exactly great, but, we do not expect to end
up there as modern Windows will use `%UserProfile%\Local Settings`
before that.

Author: compnerd

Foundation/NSPathUtilities.swift

@@ -10,13 +10,20 @@
 import CoreFoundation
 
 public func NSTemporaryDirectory() -> String {
-    #if os(macOS) || os(iOS)
+#if os(Windows)
+    var cchLength: DWORD = GetTempPathW(0, nil)
+    var wszPath: UnsafeMutableBufferPointer = UnsafeMutableBufferPointer<WCHAR>.allocate(capacity: Int(cchLength + 1))
+    defer { wszPath.deallocate() }
+    _ = GetTempPathW(cchLength + 1, wszPath.baseAddress)
+    return String(decodingCString: wszPath.baseAddress!, as: UTF16.self)
+#else
+#if os(macOS) || os(iOS)
     var buf = [Int8](repeating: 0, count: 100)
     let r = confstr(_CS_DARWIN_USER_TEMP_DIR, &buf, buf.count)
     if r != 0 && r < buf.count {
         return String(cString: buf, encoding: .utf8)!
     }
-    #endif
+#endif
     if let tmpdir = ProcessInfo.processInfo.environment["TMPDIR"] {
         if !tmpdir.hasSuffix("/") {
             return tmpdir + "/"
@@ -25,6 +32,7 @@ public func NSTemporaryDirectory() -> String {
         }
     }
     return "/tmp/"
+#endif
 }
 
 extension String {