Allow sdcard daemon to run above expanded storage.

We have a /media directory on expanded storage that behaves just
like internal storage, and has a FUSE daemon running above it.

avc: denied { search } for name="expand" dev="tmpfs" ino=3130 scontext=u:r:sdcardd:s0 tcontext=u:object_r:mnt_expand_file:s0 tclass=dir permissive=0

Bug: 19993667
Change-Id: I771ecb8f2808c48ccf4139ac9cfc2a48a2332fec

sdcardd.te

@@ -28,3 +28,6 @@ allow sdcardd install_data_file:file r_file_perms;
 # Allow stdin/out back to vold
 allow sdcardd vold:fd use;
 allow sdcardd vold:fifo_file { read write getattr };
+
+# Allow running on top of expanded storage
+allow sdcardd mnt_expand_file:dir search;