[libxml2] Fix memory leak in xmlXIncludeLoadDoc error path

[Nick Wellnhofer <nwellnhof src gnome org>]

commit ff009f991314ce8711f8a6a7f99107c10fb0a807
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Sat May 30 15:32:25 2020 +0200

    Fix memory leak in xmlXIncludeLoadDoc error path
    
    Found by OSS-Fuzz.

 xinclude.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/xinclude.c b/xinclude.c
index 5d44df4d..baeb8dbc 100644
--- a/xinclude.c
+++ b/xinclude.c
@@ -1608,6 +1608,7 @@ loaded:
                               XML_XINCLUDE_XPTR_RESULT,
                               "XPointer is not a range: #%s\n",
                               fragment);
+                xmlXPathFreeObject(xptr);
                xmlXPathFreeContext(xptrctxt);
                xmlFree(URL);
                xmlFree(fragment);
@@ -1615,6 +1616,7 @@ loaded:
            case XPATH_NODESET:
                if ((xptr->nodesetval == NULL) ||
                    (xptr->nodesetval->nodeNr <= 0)) {
+                    xmlXPathFreeObject(xptr);
                    xmlXPathFreeContext(xptrctxt);
                    xmlFree(URL);
                    xmlFree(fragment);