Fix failing FileTest#test_canonicalCachesAreOff()

FileTest#test_canonicalCachesAreOff() were passing only in
vogar, in cts they were failing to create a symlink named "test_sl".

Fixed the test by making the symlink name a valid one (that can be
created without an error).

Test: FileTest in vogar and cts
Bug: 62301183
Bug: 64598164
Change-Id: I6162d1f8e8d3dc83c5dd6a5c5f4ac68ca0204685
(cherry picked from commit 07e6e4e2af1ec4c8ef4e1d70fe55664270c4f4c9)

luni/src/test/java/libcore/java/io/FileTest.java

diff --git a/luni/src/test/java/libcore/java/io/FileTest.java b/luni/src/test/java/libcore/java/io/FileTest.java
index be28f60..04de751 100644
--- a/luni/src/test/java/libcore/java/io/FileTest.java
+++ b/luni/src/test/java/libcore/java/io/FileTest.java
@@ -371,19 +371,22 @@
 
     // http://b/62301183
     public void test_canonicalCachesAreOff() throws Exception {
-        File f1 = File.createTempFile("testCannonCachesOff1", "tmp");
-        File f2 = File.createTempFile("testCannonCachesOff2", "tmp");
-        File symlinkFile = new File("test_sl");
+        File tempDir = createTemporaryDirectory();
+        File f1 = new File(tempDir, "testCannonCachesOff1");
+        f1.createNewFile();
+        File f2  = new File(tempDir, "testCannonCachesOff2");
+        f2.createNewFile();
+        File symlinkFile = new File(tempDir, "symlink");
 
         // Create a symlink from symlink to f1 and populate canonical path cache
         assertEquals(0, Runtime.getRuntime().exec("ln -s " + f1.getAbsolutePath() + " " + symlinkFile.getAbsolutePath()).waitFor());
-        assertEquals(symlinkFile.getCanonicalPath(), f1.toString());
+        assertEquals(symlinkFile.getCanonicalPath(), f1.getCanonicalPath());
 
         // Remove it and replace it with a symlink to f2 (using java File/Files would flush caches).
         assertEquals(0, Runtime.getRuntime().exec("rm " + symlinkFile.getAbsolutePath()).waitFor());
         assertEquals(0, Runtime.getRuntime().exec("ln -s " + f2.getAbsolutePath() + " " + symlinkFile.getAbsolutePath()).waitFor());
 
         // Did we cache canonical path results? hope not!
-        assertEquals(symlinkFile.getCanonicalPath(), f2.toString());
+        assertEquals(symlinkFile.getCanonicalPath(), f2.getCanonicalPath());
     }
 }