5218 posix definition of NULL
correct unistd.h and iso/stddef_iso.h
update gate source affected

@@ -147,11 +147,11 @@
 
                         g_op_mode |= PT_MODE_DUMP;
                         g_gui = B_FALSE;
                         dump_count = (int)strtod(optarg, &endptr);
 
-                        if (dump_count <= 0 || *endptr != NULL) {
+                        if (dump_count <= 0 || *endptr != '\0') {
                                 pt_usage();
                                 exit(EXIT_USAGE);
                         }
 
                         break;

@@ -163,11 +163,11 @@
 
                         g_op_mode |= PT_MODE_TIME;
                         interval = interval_usr = (double)strtod(optarg,
                             &endptr);
 
-                        if (*endptr != NULL || interval < 1 ||
+                        if (*endptr != '\0' || interval < 1 ||
                             interval > INTERVAL_MAX) {
                                 pt_usage();
                                 exit(EXIT_USAGE);
                         }