Apply suggestions from code review

Co-authored-by: Saleem Abdulrasool <compnerd@compnerd.org>

Author: al45tair

Sources/System/FilePath/FilePathParsing.swift

@@ -335,7 +335,7 @@ extension FilePath {
 // Whether we are providing Windows paths
 @inline(__always)
 internal var _windowsPaths: Bool {
-  if let forceWindowsPaths = forceWindowsPaths {
+  if let forceWindowsPaths {
     return forceWindowsPaths
   }
   #if os(Windows)

Sources/System/FilePath/FilePathTemp.swift

@@ -50,11 +50,10 @@ fileprivate func makeLockedDownDirectory(at path: FilePath) throws -> Bool {
       return true
     }
     let err = system_errno
-    if err == Errno.fileExists.rawValue {
-      return false
-    } else {
+    guard err == Errno.fileExists.rawValue else {
       throw Errno(rawValue: err)
     }
+    return false
   }
 }
 
@@ -65,7 +64,7 @@ fileprivate func makeLockedDownDirectory(at path: FilePath) throws -> Bool {
 /// - Returns: A random string of length `length`.
 fileprivate func createRandomString(length: Int) -> String {
   return String(
-    decoding: (0..<length).map{
+    decoding: (0..<length).map {
       _ in base64[Int.random(in: 0..<64)]
     },
     as: UTF8.self