The return value of snprintf maybe over the size of TMPBUFLEN, use
scnprintf instead in sel_read_class and sel_read_perm.
Change-Id: I201906f885655f9490de5ed0924c7bd41c4c513d
Signed-off-by: liuyang34 <liuyang34@xiaomi.com>
[PM: cleaned up the description]
Signed-off-by: Paul Moore <paul@paul-moore.com>