Don't specialcase temporary folder generation on windows

With new gradle we don't have build/tmp, and tests run fine without this

Change-Id: I60676da96b3cd2a21989f43c64c85966dea94362
diff --git a/src/test/java/com/android/tools/r8/ToolHelper.java b/src/test/java/com/android/tools/r8/ToolHelper.java
index 244493d..d209cb8 100644
--- a/src/test/java/com/android/tools/r8/ToolHelper.java
+++ b/src/test/java/com/android/tools/r8/ToolHelper.java
@@ -1289,7 +1289,7 @@
   public static TemporaryFolder getTemporaryFolderForTest() {
     String tmpDir = System.getProperty("test_dir");
     if (tmpDir == null) {
-      return new TemporaryFolder(ToolHelper.isLinux() ? null : Paths.get("build", "tmp").toFile());
+      return new TemporaryFolder();
     } else {
       return new RetainedTemporaryFolder(new java.io.File(tmpDir));
     }