[libxml2] Fix memory leak in xmlFreeParserInputBuffer

[Nick Wellnhofer <nwellnhof src gnome org>]

commit e7d1c53a49cac5eab6324809d169ec94c87f4699
Author: David King <amigadave amigadave com>
Date:   Wed Jul 14 11:32:57 2021 +0100

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

 HTMLparser.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/HTMLparser.c b/HTMLparser.c
index 9769ad5b..ebf2641f 100644
--- a/HTMLparser.c
+++ b/HTMLparser.c
@@ -5197,6 +5197,7 @@ htmlCreateMemoryParserCtxt(const char *buffer, int size) {
 
     input = xmlNewInputStream(ctxt);
     if (input == NULL) {
+       xmlFreeParserInputBuffer(buf);
        xmlFreeParserCtxt(ctxt);
        return(NULL);
     }