write_in_full: size_t is unsigned.

It received the return value from xwrite() in a size_t variable
'written' and expected comparison with 0 would catch an error
from xwrite().

Signed-off-by: Junio C Hamano <junkio@cox.net>

write_or_die.c

@@ -23,7 +23,7 @@ int write_in_full(int fd, const void *buf, size_t count)
 	ssize_t total = 0;
 
 	while (count > 0) {
-		size_t written = xwrite(fd, p, count);
+		ssize_t written = xwrite(fd, p, count);
 		if (written < 0)
 			return -1;
 		if (!written) {