Fix crash by "adb shell pm list permissions -f|-s"

pm command makes the assumption that every permission should
contain android:description and android:label attributes while
they are not mandatory. If a permission does not contain these
two attributes, we get "android.content.res.
Resources$NotFoundException: String resource ID #0x0"
followed by a NPE when using -f or -s options.

With the following change, users will get "null" in output for
respective fields.

Change-Id: I4e7f407592fa071abdab1d979775f46ec27dc9d2

Author: Ali Utku Selen

cmds/pm/src/com/android/commands/pm/Pm.java

@@ -341,9 +341,11 @@ private String loadText(PackageItemInfo pii, int res, CharSequence nonLocalized)
         if (nonLocalized != null) {
             return nonLocalized.toString();
         }
-        Resources r = getResources(pii);
-        if (r != null) {
-            return r.getString(res);
+        if (res != 0) {
+            Resources r = getResources(pii);
+            if (r != null) {
+                return r.getString(res);
+            }
         }
         return null;
     }