timestamping: fix example build

Fix Makefiles so that Documentation/networking/timestamping/timestamping.c
will build when using the CONFIG_BUILD_DOCSRC kconfig option.
(timestamping.c does not build currently with its simple Makefile.)

Also fix printf format warnings.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Patrick Ohly <patrick.ohly@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/Makefile

@@ -6,3 +6,5 @@ hostprogs-y := ifenslave
 
 # Tell kbuild to always build the programs
 always := $(hostprogs-y)
+
+obj-m := timestamping/

Documentation/networking/timestamping/Makefile

@@ -1,6 +1,13 @@
-CPPFLAGS = -I../../../include
+# kbuild trick to avoid linker error. Can be omitted if a module is built.
+obj- := dummy.o
 
-timestamping: timestamping.c
+# List of programs to build
+hostprogs-y := timestamping
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)
+
+HOSTCFLAGS_timestamping.o += -I$(objtree)/usr/include
 
 clean:
 	rm -f timestamping

Documentation/networking/timestamping/timestamping.c

@@ -41,9 +41,9 @@
 #include <arpa/inet.h>
 #include <net/if.h>
 
-#include "asm/types.h"
-#include "linux/net_tstamp.h"
-#include "linux/errqueue.h"
+#include <asm/types.h>
+#include <linux/net_tstamp.h>
+#include <linux/errqueue.h>
 
 #ifndef SO_TIMESTAMPING
 # define SO_TIMESTAMPING         37
@@ -164,7 +164,7 @@ static void printpacket(struct msghdr *msg, int res,
 
 	gettimeofday(&now, 0);
 
-	printf("%ld.%06ld: received %s data, %d bytes from %s, %d bytes control messages\n",
+	printf("%ld.%06ld: received %s data, %d bytes from %s, %zu bytes control messages\n",
 	       (long)now.tv_sec, (long)now.tv_usec,
 	       (recvmsg_flags & MSG_ERRQUEUE) ? "error" : "regular",
 	       res,
@@ -173,7 +173,7 @@ static void printpacket(struct msghdr *msg, int res,
 	for (cmsg = CMSG_FIRSTHDR(msg);
 	     cmsg;
 	     cmsg = CMSG_NXTHDR(msg, cmsg)) {
-		printf("   cmsg len %d: ", cmsg->cmsg_len);
+		printf("   cmsg len %zu: ", cmsg->cmsg_len);
 		switch (cmsg->cmsg_level) {
 		case SOL_SOCKET:
 			printf("SOL_SOCKET ");