procqueue: allocate an output buffer as named chunk

The talloc_size() call sets the current file name and the current
line number as name for chunk being allocated. This combination
is not so informative during debugging, so let's use the static
'.buffer' string as context name for item's output buffer.

src/procqueue.c

@@ -174,7 +174,7 @@ osmo_gapk_pq_prepare(struct osmo_gapk_pq *pq)
 				buf_size = VAR_BUF_SIZE;
 
 			/* Allocate memory for an output buffer */
-			item->buf = talloc_size(item, buf_size);
+			item->buf = talloc_named_const(item, buf_size, ".buffer");
 			if (!item->buf)
 				return -ENOMEM;
 		}