Clarify vold isn't exploitable when no sd card exists

Change-Id: I24903ca0f6267c0034df068abcece6091f25f38e
diff --git a/tests/tests/security/src/android/security/cts/VoldExploitTest.java b/tests/tests/security/src/android/security/cts/VoldExploitTest.java
index df5e58a..38eece7 100644
--- a/tests/tests/security/src/android/security/cts/VoldExploitTest.java
+++ b/tests/tests/security/src/android/security/cts/VoldExploitTest.java
@@ -51,8 +51,8 @@
         devices.addAll(getSysFsPath("/etc/vold.fstab"));
         devices.addAll(getSysFsPath("/system/etc/vold.fstab"));
         if (devices.isEmpty()) {
-          // FIXME: We should be able to detect this security hole
-          // even if there's no vold.fstab entry
+          // This vulnerability is not exploitable if there's
+          // no entry in vold.fstab
           return;
         }