BUG/MINOR: ssl/cli: fix a potential NULL dereference

Fix a potential NULL dereference in "show ssl cert" when we can't
allocate the <out> trash buffer.

This patch creates a new label so we could jump without trying to do the
ci_putchk in this case.

This bug was introduced by ea987ed ("MINOR: ssl/cli: 'new ssl cert'
command"). 2.2 only.

This bug was referenced by issue #556.
diff --git a/src/ssl_sock.c b/src/ssl_sock.c
index bf571dd..9b44e9d 100644
--- a/src/ssl_sock.c
+++ b/src/ssl_sock.c
@@ -11249,7 +11249,7 @@
 	int i;
 
 	if (!tmp || !out)
-		goto end;
+		goto end_no_putchk;
 
 	if (!ckchs->multi) {
 		chunk_appendf(out, "Filename: ");
@@ -11374,6 +11374,7 @@
 		goto yield;
 	}
 
+end_no_putchk:
 	if (bio)
 		BIO_free(bio);
 	free_trash_chunk(tmp);