selinux: generate flask headers during kernel build

Add a simple utility (scripts/selinux/genheaders) and invoke it to
generate the kernel-private class and permission indices in flask.h
and av_permissions.h automatically during the kernel build from the
security class mapping definitions in classmap.h.  Adding new kernel
classes and permissions can then be done just by adding them to classmap.h.

Signed-off-by:  Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/scripts/selinux/genheaders/Makefile b/scripts/selinux/genheaders/Makefile
new file mode 100644
index 0000000..417b165
--- /dev/null
+++ b/scripts/selinux/genheaders/Makefile
@@ -0,0 +1,5 @@
+hostprogs-y	:= genheaders
+HOST_EXTRACFLAGS += -Isecurity/selinux/include
+
+always		:= $(hostprogs-y)
+clean-files	:= $(hostprogs-y)