[libxml2] Fix memory leak in xmlCreateIOParserCtxt

[Nick Wellnhofer <nwellnhof src gnome org>]

commit fe564967c97c5059a0d95401f73d3c741613fe14
Author: David King <amigadave amigadave com>
Date:   Wed Jul 14 14:35:17 2021 +0100

    Fix memory leak in xmlCreateIOParserCtxt
    
    Found by Coverity.
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1938806

 parser.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/parser.c b/parser.c
index 255bd254..0737b7f7 100644
--- a/parser.c
+++ b/parser.c
@@ -12625,6 +12625,7 @@ xmlCreateIOParserCtxt(xmlSAXHandlerPtr sax, void *user_data,
            xmlFree(ctxt->sax);
        ctxt->sax = (xmlSAXHandlerPtr) xmlMalloc(sizeof(xmlSAXHandler));
        if (ctxt->sax == NULL) {
+           xmlFreeParserInputBuffer(buf);
            xmlErrMemory(ctxt, NULL);
            xmlFreeParserCtxt(ctxt);
            return(NULL);