recovery: allow relabelto unlabeled and other unlabeled rules

The recovery script may ask to label a file with a label not
known to the currently loaded policy. Allow it.

Addresses the following denials:

  avc:  denied  { relabelto } for  pid=143 comm="update_binary" name="vdc" dev="mmcblk0p25" ino=212 scontext=u:r:recovery:s0 tcontext=u:object_r:unlabeled:s0 tclass=file
  avc:  denied  { setattr } for  pid=143 comm="update_binary" name="vdc" dev="mmcblk0p25" ino=212 scontext=u:r:recovery:s0 tcontext=u:object_r:unlabeled:s0 tclass=file

Change-Id: Iafcc7b0b3aaea5a272adb1264233978365648f94

recovery.te

@@ -30,6 +30,11 @@ recovery_only(`
   allow recovery system_file:{ file lnk_file } { create_file_perms relabelfrom relabelto };
   allow recovery system_file:dir { create_dir_perms relabelfrom relabelto };
 
+  # We may be asked to set an SELinux label for a type not known to the
+  # currently loaded policy. Allow it.
+  allow recovery unlabeled:file { create_file_perms relabelfrom relabelto };
+  allow recovery unlabeled:dir { create_dir_perms relabelfrom relabelto };
+
   # 0eb17d944704b3eb140bb9dded299d3be3aed77e in build/ added SELinux
   # support to OTAs. However, that code has a bug. When an update occurs,
   # some directories are inappropriately labeled as exec_type. This is