Make fread/fwrite-like functions in http.c more like fread/fwrite.

The fread/fwrite-like functions in http.c, namely fread_buffer,
fwrite_buffer, fwrite_null, fwrite_sha1_file all return the
multiplication of the size and number of items they are being given.

Practically speaking, it doesn't matter, because in all contexts where
those functions are used, size is 1.

But those functions being similar to fread and fwrite (the curl API is
designed around being able to use fread and fwrite directly), it might
be preferable to make them behave like fread and fwrite, which, from
the fread/fwrite manual page, is:
   On  success, fread() and fwrite() return the number of items read
   or written.  This number equals the number of bytes transferred
   only when size is 1.  If an error occurs, or the end of the file
   is reached, the return value is a short item count (or zero).

Signed-off-by: Mike Hommey <mh@glandium.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

http.c

@@ -176,7 +176,7 @@ size_t fread_buffer(char *ptr, size_t eltsize, size_t nmemb, void *buffer_)
 	memcpy(ptr, buffer->buf.buf + buffer->posn, size);
 	buffer->posn += size;
 
-	return size;
+	return size / eltsize;
 }
 
 #ifndef NO_CURL_IOCTL
@@ -204,12 +204,12 @@ size_t fwrite_buffer(char *ptr, size_t eltsize, size_t nmemb, void *buffer_)
 	struct strbuf *buffer = buffer_;
 
 	strbuf_add(buffer, ptr, size);
-	return size;
+	return nmemb;
 }
 
 size_t fwrite_null(char *ptr, size_t eltsize, size_t nmemb, void *strbuf)
 {
-	return eltsize * nmemb;
+	return nmemb;
 }
 
 static void closedown_active_slot(struct active_request_slot *slot)
@@ -2319,14 +2319,14 @@ static size_t fwrite_sha1_file(char *ptr, size_t eltsize, size_t nmemb,
 			BUG("curl_easy_getinfo for HTTP code failed: %s",
 				curl_easy_strerror(c));
 		if (slot->http_code >= 300)
-			return size;
+			return nmemb;
 	}
 
 	do {
 		ssize_t retval = xwrite(freq->localfile,
 					(char *) ptr + posn, size - posn);
 		if (retval < 0)
-			return posn;
+			return posn / eltsize;
 		posn += retval;
 	} while (posn < size);
 
@@ -2339,7 +2339,7 @@ static size_t fwrite_sha1_file(char *ptr, size_t eltsize, size_t nmemb,
 		the_hash_algo->update_fn(&freq->c, expn,
 					 sizeof(expn) - freq->stream.avail_out);
 	} while (freq->stream.avail_in && freq->zret == Z_OK);
-	return size;
+	return nmemb;
 }
 
 struct http_object_request *new_http_object_request(const char *base_url,