[libxml2] Fix memory leak in xmlFindCharEncodingHandler

[Nick Wellnhofer <nwellnhof src gnome org>]

commit f2072a8b2fcfcf6ca30b9eae8d4e9a10c61192bd
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Sat Mar 5 18:23:34 2022 +0100

    Fix memory leak in xmlFindCharEncodingHandler
    
    Fix memory leak in an unlikely error condition. Thanks to Wentao Liang
    for the report.
    
    Fixes #342.

 encoding.c | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/encoding.c b/encoding.c
index 951c5285..fc5373c4 100644
--- a/encoding.c
+++ b/encoding.c
@@ -1747,6 +1747,10 @@ xmlFindCharEncodingHandler(const char *name) {
     } else if ((icv_in != (iconv_t) -1) || icv_out != (iconv_t) -1) {
            xmlEncodingErr(XML_ERR_INTERNAL_ERROR,
                    "iconv : problems with filters for '%s'\n", name);
+           if (icv_in != (iconv_t) -1)
+               iconv_close(icv_in);
+           else
+               iconv_close(icv_out);
     }
 #endif /* LIBXML_ICONV_ENABLED */
 #ifdef LIBXML_ICU_ENABLED