ringlogger: support mpsc for singlefile

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

WireGuard/Shared/FileManager+Extension.swift

@@ -27,7 +27,7 @@ extension FileManager {
         return sharedFolderURL
     }
 
-    static var networkExtensionLogFileURL: URL? {
+    static var logFileURL: URL? {
         return sharedFolderURL?.appendingPathComponent("tunnel-log.bin")
     }
 
@@ -35,14 +35,6 @@ extension FileManager {
         return sharedFolderURL?.appendingPathComponent("last-error.txt")
     }
 
-    static var appLogFileURL: URL? {
-        guard let documentDirURL = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask).first else {
-            wg_log(.error, message: "Cannot obtain app documents folder URL")
-            return nil
-        }
-        return documentDirURL.appendingPathComponent("app-log.bin")
-    }
-
     static func deleteFile(at url: URL) -> Bool {
         do {
             try FileManager.default.removeItem(at: url)