OS-4807 arp(1M) and ndp(1M) should use zone_get_nroot()

@@ -56,10 +56,11 @@
 #include <unistd.h>
 #include <string.h>
 #include <arpa/inet.h>
 #include <net/if_types.h>
 #include <net/if_dl.h>
+#include <zone.h>
 
 static int file(char *);
 static int set(int, char *[]);
 static void get(char *);
 static void delete(char *);

@@ -116,15 +117,19 @@
                 /*
                  * the easiest way to get the complete arp table
                  * is to let netstat, which prints it as part of
                  * the MIB statistics, do it.
                  */
-                (void) execl("/usr/bin/netstat", "netstat",
+                char netstat_path[MAXPATHLEN];
+                const char *zroot = zone_get_nroot();
+                (void) snprintf(netstat_path, sizeof (netstat_path), "%s%s", zroot != NULL ?
+                    zroot : "", "/usr/bin/netstat");
+                (void) execl(netstat_path, "netstat",
                     (n_flag ? "-np" : "-p"),
                     "-f", "inet", (char *)0);
-                (void) fprintf(stderr, "failed to exec netstat: %s\n",
-                    strerror(errno));
+                (void) fprintf(stderr, "failed to exec %s: %s\n",
+                    netstat_path, strerror(errno));
                 exit(1);
 
         } else if (s_flag && (argsleft >= 2)) {
                 if (set(argsleft, &argv[optind]) != 0)
                         exit(1);