short i/o: fix calls to write to use xwrite or write_in_full

We have a number of badly checked write() calls.  Often we are
expecting write() to write exactly the size we requested or fail,
this fails to handle interrupts or short writes.  Switch to using
the new write_in_full().  Otherwise we at a minimum need to check
for EINTR and EAGAIN, where this is appropriate use xwrite().

Note, the changes to config handling are much larger and handled
in the next patch in the sequence.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

http-fetch.c

@@ -71,7 +71,7 @@ static size_t fwrite_sha1_file(void *ptr, size_t eltsize, size_t nmemb,
 	int posn = 0;
 	struct object_request *obj_req = (struct object_request *)data;
 	do {
-		ssize_t retval = write(obj_req->local,
+		ssize_t retval = xwrite(obj_req->local,
 				       (char *) ptr + posn, size - posn);
 		if (retval < 0)
 			return posn;