usleep: do not check for usleep error, it should never fail

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/coreutils/usleep.c b/coreutils/usleep.c
index 67f94f7..2e4eb57 100644
--- a/coreutils/usleep.c
+++ b/coreutils/usleep.c
@@ -29,9 +29,7 @@
 		bb_show_usage();
 	}
 
-	if (usleep(xatou(argv[1]))) {
-		bb_perror_nomsg_and_die();
-	}
+	usleep(xatou(argv[1]));
 
 	return EXIT_SUCCESS;
 }