ANDROID: quick selinux support for tracefs

Here is just the quick fix for tracefs with selinux.
just add tracefs to the list of whitelisted filesystem
types in selinux_is_sblabel_mnt(), but the right fix would be to
generalize this logic as described in the last item on the todo list,
https://bitbucket.org/seandroid/wiki/wiki/ToDo

Change-Id: I2aa803ccffbcd2802a7287514da7648e6b364157
Signed-off-by: Yongqin Liu <yongqin.liu@linaro.org>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 09fd610..24bd84d 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -491,6 +491,7 @@
 		!strcmp(sb->s_type->name, "sysfs") ||
 		!strcmp(sb->s_type->name, "pstore") ||
 		!strcmp(sb->s_type->name, "debugfs") ||
+		!strcmp(sb->s_type->name, "tracefs") ||
 		!strcmp(sb->s_type->name, "rootfs");
 }