Don't print an error if the utmp file doesn't exist, getutent will return

NULL as expected.

libc/misc/utmp/utent.c

@@ -33,7 +33,6 @@ void setutent(void)
 	if (ut_fd != -1)
 		close(ut_fd);
 	if ((ut_fd = open(ut_name, O_RDONLY)) < 0) {
-		perror("setutent: Can't open utmp file");
 		ut_fd = -1;
 	}
 }