[libxml2] Fix call stack overflow in xmlFreePattern

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 346febc6abbd63d1fa6a532c7429d2c11b5c269b
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Thu Apr 25 11:34:08 2019 +0200

    Fix call stack overflow in xmlFreePattern
    
    Since xmlFreePattern tried to free the next pattern recursively, its
    behavior is identical to xmlFreePatternList. Make it call
    xmlFreePatternList to avoid call stack overflows.
    
    Found by OSS-Fuzz.

 pattern.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)
---
diff --git a/pattern.c b/pattern.c
index 0eb8d812..fdf5c79d 100644
--- a/pattern.c
+++ b/pattern.c
@@ -229,13 +229,16 @@ xmlNewPattern(void) {
  */
 void
 xmlFreePattern(xmlPatternPtr comp) {
+    xmlFreePatternList(comp);
+}
+
+static void
+xmlFreePatternInternal(xmlPatternPtr comp) {
     xmlStepOpPtr op;
     int i;
 
     if (comp == NULL)
        return;
-    if (comp->next != NULL)
-        xmlFreePattern(comp->next);
     if (comp->stream != NULL)
         xmlFreeStreamComp(comp->stream);
     if (comp->pattern != NULL)
@@ -273,7 +276,7 @@ xmlFreePatternList(xmlPatternPtr comp) {
        cur = comp;
        comp = comp->next;
        cur->next = NULL;
-       xmlFreePattern(cur);
+       xmlFreePatternInternal(cur);
     }
 }