net/ipv4/sysctl_net_ipv4.c: remove superfluous header files from sysctl_net_ipv4.c

sysctl_net_ipv4.c hasn't use any macro or function declared in igmp.h,
inetdevice.h, mm.h, module.h, nsproxy.h, swap.h, inet_frag.h, route.h
and snmp.h. Thus, these files can be removed from sysctl_net_ipv4.c
safely without affecting the compilation of the net module.
Signed-off-by: Mianhan Liu <liumh1@shanghaitech.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/sysctl_net_ipv4.c

@@ -6,25 +6,16 @@
  * Added /proc/sys/net/ipv4 directory entry (empty =) ). [MS]
  */
 
-#include <linux/mm.h>
-#include <linux/module.h>
 #include <linux/sysctl.h>
-#include <linux/igmp.h>
-#include <linux/inetdevice.h>
 #include <linux/seqlock.h>
 #include <linux/init.h>
 #include <linux/slab.h>
-#include <linux/nsproxy.h>
-#include <linux/swap.h>
-#include <net/snmp.h>
 #include <net/icmp.h>
 #include <net/ip.h>
 #include <net/ip_fib.h>
-#include <net/route.h>
 #include <net/tcp.h>
 #include <net/udp.h>
 #include <net/cipso_ipv4.h>
-#include <net/inet_frag.h>
 #include <net/ping.h>
 #include <net/protocol.h>
 #include <net/netevent.h>