[NET]: Add const markers to various variables.

the patch below marks various variables const in net/; the goal is to
move them to the .rodata section so that they can't false-share
cachelines with things that get written to, as well as potentially
helping gcc a bit with optimisations.  (these were found using a gcc
patch to warn about such variables)

Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index e3eceec..92e23b2 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -220,7 +220,7 @@
 	short   error;		/* This ICMP is classed as an error message */
 };
 
-static struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
+static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
 
 /*
  *	The ICMP socket(s). This is the most convenient way to flow control
@@ -994,7 +994,7 @@
 /*
  *	This table is the definition of how we handle ICMP.
  */
-static struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
+static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
 	[ICMP_ECHOREPLY] = {
 		.output_entry = ICMP_MIB_OUTECHOREPS,
 		.input_entry = ICMP_MIB_INECHOREPS,