sepolicy: treat fuseblk as sdcard_external

Allow fuse-mounted NTFS/exFAT file systems to be written to

Change-Id: I1492914dd269a305e27aba58e61064d853adf2bc
sepolicy: allow installd to query ASEC size

installd need to query ASEC size on sdcard_external
to show on the Settings -> Apps page correctly.

Change-Id: I2d9a49b8f0652f05d73d0ff464a3835595e2cc3c