pkt-line: drop safe_write function

This is just write_or_die by another name. The one
distinction is that write_or_die will treat EPIPE specially
by suppressing error messages. That's fine, as we die by
SIGPIPE anyway (and in the off chance that it is disabled,
write_or_die will simulate it).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/send-pack.c

@@ -79,7 +79,7 @@ static void print_helper_status(struct ref *ref)
 		}
 		strbuf_addch(&buf, '\n');
 
-		safe_write(1, buf.buf, buf.len);
+		write_or_die(1, buf.buf, buf.len);
 	}
 	strbuf_release(&buf);
 }