Remove use of deprecated STSC 'Lock'

- SwiftScan use of it seems not needed anymore
- ArgsResolver use can use 'NSLock' directly

Author: artemcm

Sources/SwiftDriver/Execution/ArgsResolver.swift

@@ -10,6 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+import class Foundation.NSLock
 import TSCBasic
 @_implementationOnly import Yams
 
@@ -25,7 +26,7 @@ public final class ArgsResolver {
   // FIXME: We probably need a dedicated type for this...
   private let temporaryDirectory: VirtualPath
 
-  private let lock = Lock()
+  private let lock = NSLock()
 
   public init(fileSystem: FileSystem, temporaryDirectory: VirtualPath? = nil) throws {
     self.pathMapping = [:]

Sources/SwiftDriver/SwiftScan/SwiftScan.swift

@@ -63,9 +63,6 @@ internal final class SwiftScan {
   /// The handle to the dylib.
   let dylib: Loader.Handle
 
-  /// Lock protecting private state.
-  let lock: Lock = Lock()
-
   /// libSwiftScan API functions.
   let api: swiftscan_functions_t;