netlink: Move netlink attribute parsing support to lib

Netlink attribute parsing may be used even if CONFIG_NET is not set.
Move it from net/netlink to lib and control its inclusion based on the new
config symbol CONFIG_NLATTR, which is selected by CONFIG_NET.

Signed-off-by: Geert Uytterhoeven <[e-mail]>
Acked-by: David S. Miller <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

lib/Kconfig

···
        bool "Disable obsolete cpumask functions" if DEBUG_PER_CPU_MAPS
        depends on EXPERIMENTAL && BROKEN
 
+#
+# Netlink attribute parsing support is select'ed if needed
+#
+config NLATTR
+	bool
+
 endmenu

lib/Makefile

···
 
 obj-$(CONFIG_DYNAMIC_PRINTK_DEBUG) += dynamic_printk.o
 
+obj-$(CONFIG_NLATTR) += nlattr.o
+
 hostprogs-y	:= gen_crc32table
 clean-files	:= crc32table.h
 

net/Kconfig

···
 
 menuconfig NET
 	bool "Networking support"
+	select NLATTR
 	---help---
 	  Unless you really know what you are doing, you should say Y here.
 	  The reason is that some programs need kernel networking support even

net/netlink/Makefile

···
 # Makefile for the netlink driver.
 #
 
-obj-y  				:= af_netlink.o attr.o genetlink.o
+obj-y  				:= af_netlink.o genetlink.o