libbb: shrink lineedit_read_key()

function                                             old     new   delta
lineedit_read_key                                    237     231      -6

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

libbb/read_key.c

@@ -291,6 +291,7 @@ int64_t FAST_FUNC safe_read_key(int fd, char *buffer, int timeout)
 {
 	int64_t r;
 	do {
+		/* errno = 0; - read_key does this itself */
 		r = read_key(fd, buffer, timeout);
 	} while (errno == EINTR);
 	return r;