[libxslt] Don't pass first <xsl:sort> in <xsl:apply-templates> twice

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 6a84b3e236f34ee2d2a257a484a3593c221c4e70
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Sat Dec 19 16:31:18 2020 +0100

    Don't pass first <xsl:sort> in <xsl:apply-templates> twice
    
    Fix a long-standing issue that would create an additional copy of the
    first <xsl:sort> element inside <xsl:apply-templates>, slowing down
    sorting.

 libxslt/transform.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/libxslt/transform.c b/libxslt/transform.c
index d1c47932..04522154 100644
--- a/libxslt/transform.c
+++ b/libxslt/transform.c
@@ -5121,6 +5121,7 @@ xsltApplyTemplates(xsltTransformContextPtr ctxt, xmlNodePtr node,
                xmlNodePtr sorts[XSLT_MAX_SORT];
 
                sorts[nbsorts++] = cur;
+               cur = cur->next;
 
                while (cur) {