[libxml2] Fix xmlParserEntityCheck

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 707ad080e61014ab4a6d60dc12875e233c1f673c
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Tue Jan 23 16:37:54 2018 +0100

    Fix xmlParserEntityCheck
    
    A previous commit removed the check for XML_ERR_ENTITY_LOOP which is
    required to abort early in case of excessive entity recursion.

 parser.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/parser.c b/parser.c
index 5e800e1..ca9fde2 100644
--- a/parser.c
+++ b/parser.c
@@ -149,7 +149,7 @@ xmlParserEntityCheck(xmlParserCtxtPtr ctxt, size_t size,
        rep = xmlStringDecodeEntities(ctxt, ent->content,
                                  XML_SUBSTITUTE_REF, 0, 0, 0);
         --ctxt->depth;
-       if (rep == NULL) {
+       if ((rep == NULL) || (ctxt->errNo == XML_ERR_ENTITY_LOOP)) {
            ent->content[0] = 0;
        }