samples/bpf: adjust rlimit RLIMIT_MEMLOCK for xdp_redirect

Default rlimit RLIMIT_MEMLOCK is 64KB, causes bpf map failure.
e.g.
[root@labbpf]# ./xdp_redirect $(</sys/class/net/eth2/ifindex) \
> $(</sys/class/net/eth3/ifindex)
failed to create a map: 1 Operation not permitted

The failure is seen when executing xdp_redirect while xdp_monitor
is already runnig.
Signed-off-by: Tushar Dave <tushar.n.dave@oracle.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

samples/bpf/xdp_redirect_user.c

@@ -20,6 +20,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <libgen.h>
+#include <sys/resource.h>
 
 #include "bpf_load.h"
 #include "bpf_util.h"
@@ -75,6 +76,7 @@ static void usage(const char *prog)
 
 int main(int argc, char **argv)
 {
+	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
 	const char *optstr = "SN";
 	char filename[256];
 	int ret, opt, key = 0;
@@ -98,6 +100,11 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
+	if (setrlimit(RLIMIT_MEMLOCK, &r)) {
+		perror("setrlimit(RLIMIT_MEMLOCK)");
+		return 1;
+	}
+
 	ifindex_in = strtoul(argv[optind], NULL, 0);
 	ifindex_out = strtoul(argv[optind + 1], NULL, 0);
 	printf("input: %d output: %d\n", ifindex_in, ifindex_out);