sepolicy: treat fuseblk as sdcard_external

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

Change-Id: I1492914dd269a305e27aba58e61064d853adf2bc
diff --git a/sepolicy/sepolicy.mk b/sepolicy/sepolicy.mk
index f45c38f..bde93dc 100644
--- a/sepolicy/sepolicy.mk
+++ b/sepolicy/sepolicy.mk
@@ -10,5 +10,6 @@
     file.te \
     file_contexts \
     fs_use \
+    genfs_contexts \
     seapp_contexts \
     mac_permissions.xml