Test fixes for RedHat

- SR-7747: FileManager.attributesOfFileSystem(forPath:) may return
  .systemNumber as 0 on some systems (eg tmpfs on Redhat).

- SR-7748: Avoid using a symlinked directory for 'pwd' test.

Author: spevans

TestFoundation/TestFileManager.swift

@@ -279,7 +279,6 @@ class TestFileManager : XCTestCase {
 
             let systemNumber = attrs[.systemNumber] as? NSNumber
             XCTAssertNotNil(systemNumber)
-            XCTAssertNotEqual(systemNumber!.uint64Value, 0)
 
             let systemFreeSize = attrs[.systemFreeSize] as? NSNumber
             XCTAssertNotNil(systemFreeSize)

TestFoundation/TestProcess.swift

@@ -280,8 +280,8 @@ class TestProcess : XCTestCase {
             let previousWorkingDirectory = FileManager.default.currentDirectoryPath
 
             // Darwin Foundation requires the full path to the executable (.launchPath)
-            let (output, _) = try runTask(["/bin/bash", "-c", "pwd"], currentDirectoryPath: "/bin")
-            XCTAssertEqual(output.trimmingCharacters(in: .newlines), "/bin")
+            let (output, _) = try runTask(["/bin/bash", "-c", "pwd"], currentDirectoryPath: "/")
+            XCTAssertEqual(output.trimmingCharacters(in: .newlines), "/")
             XCTAssertEqual(previousWorkingDirectory, FileManager.default.currentDirectoryPath)
         } catch let error {
             XCTFail("Test failed: \(error)")