selinux: fix Makefile dependencies of flask.h

stable inclusion
from stable-v5.10.180
commit fea3144639269d37923f7a88906b3fa7f1231603
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8DDFN

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fea3144639269d37923f7a88906b3fa7f1231603



--------------------------------

[ Upstream commit bcab1ade ]

Make the flask.h target depend on the genheaders binary instead of
classmap.h to ensure that it is rebuilt if any of the dependencies of
genheaders are changed.

Notably this fixes flask.h not being rebuilt when
initial_sid_to_string.h is modified.

Fixes: 8753f6be ("selinux: generate flask headers during kernel build")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>