BUG/MINOR: ssl_ckch: Dump CRL transaction only once if show command yield

When loaded CRL files are displayed via "show ssl crl-file" command, the
in-progess transaction, if any, is also displayed. However, if the command
yield, the transaction is re-displayed again and again.

To fix the issue, old_crlfile_entry field is used to remember the transaction
was already displayed.

This patch must be backported as far as 2.5.
diff --git a/src/ssl_ckch.c b/src/ssl_ckch.c
index 601cec9..5a08bc7 100644
--- a/src/ssl_ckch.c
+++ b/src/ssl_ckch.c
@@ -3762,11 +3762,12 @@
 	if (trash == NULL)
 		return 1;
 
-	if (!ctx->old_crlfile_entry) {
-		if (crlfile_transaction.old_crlfile_entry) {
-			chunk_appendf(trash, "# transaction\n");
-			chunk_appendf(trash, "*%s\n", crlfile_transaction.old_crlfile_entry->path);
-		}
+	if (!ctx->old_crlfile_entry && crlfile_transaction.old_crlfile_entry) {
+		chunk_appendf(trash, "# transaction\n");
+		chunk_appendf(trash, "*%s\n", crlfile_transaction.old_crlfile_entry->path);
+		if (applet_putchk(appctx, trash) == -1)
+			goto yield;
+		ctx->old_crlfile_entry = crlfile_transaction.old_crlfile_entry;
 	}
 
 	/* First time in this io_handler. */