selinux: don't use make's grouped targets feature yet

commit 42c4e97e06 upstream.

The Linux Kernel currently only requires make v3.82 while the grouped
target functionality requires make v4.3.  Removed the grouped target
introduced in 4ce1f694eb ("selinux: ensure av_permissions.h is
built when needed") as well as the multiple header file targets in
the make rule.  This effectively reverts the problem commit.

We will revisit this change when make >= 4.3 is required by the rest
of the kernel.

Cc: stable@vger.kernel.org
Fixes: 4ce1f694eb ("selinux: ensure av_permissions.h is built when needed")
Reported-by: Erwan Velu <e.velu@criteo.com>
Reported-by: Luiz Capitulino <luizcap@amazon.com>
Tested-by: Luiz Capitulino <luizcap@amazon.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

security/selinux/Makefile

@@ -26,5 +26,9 @@ quiet_cmd_flask = GEN     $(obj)/flask.h $(obj)/av_permissions.h
       cmd_flask = $< $(obj)/flask.h $(obj)/av_permissions.h
 
 targets += flask.h av_permissions.h
-$(obj)/flask.h $(obj)/av_permissions.h &: scripts/selinux/genheaders/genheaders FORCE
+# once make >= 4.3 is required, we can use grouped targets in the rule below,
+# which basically involves adding both headers and a '&' before the colon, see
+# the example below:
+#   $(obj)/flask.h $(obj)/av_permissions.h &: scripts/selinux/...
+$(obj)/flask.h: scripts/selinux/genheaders/genheaders FORCE
 	$(call if_changed,flask)