Network Drop Monitor: Add trace declaration for skb frees

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>

 include/trace/skb.h   |    8 ++++++++
 net/core/Makefile     |    2 ++
 net/core/net-traces.c |   29 +++++++++++++++++++++++++++++
 3 files changed, 39 insertions(+)
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/Makefile b/net/core/Makefile
index 26a37cb3192..d47092b 100644
--- a/net/core/Makefile
+++ b/net/core/Makefile
@@ -17,3 +17,5 @@
 obj-$(CONFIG_NETPOLL) += netpoll.o
 obj-$(CONFIG_NET_DMA) += user_dma.o
 obj-$(CONFIG_FIB_RULES) += fib_rules.o
+obj-$(CONFIG_TRACEPOINTS) += net-traces.o
+