Improve HTML fuzzer stability

Call htmlInitAutoClose during fuzzer initialization to fix stability
issue. Leave a note concerning problems with this function.

HTMLparser.c

@@ -1324,6 +1324,10 @@ htmlCheckAutoClose(const xmlChar * newtag, const xmlChar * oldtag)
     int i, indx;
     const char **closed = NULL;
 
+    /*
+     * FIXME: This is not thread-safe and should be called from
+     * xmlInitParser instead.
+     */
     if (htmlStartCloseIndexinitialized == 0)
         htmlInitAutoClose();
 

fuzz/html.c

@@ -6,12 +6,14 @@
 
 #include <libxml/HTMLparser.h>
 #include <libxml/HTMLtree.h>
+#include <libxml/parserInternals.h>
 #include "fuzz.h"
 
 int
 LLVMFuzzerInitialize(int *argc ATTRIBUTE_UNUSED,
                      char ***argv ATTRIBUTE_UNUSED) {
     xmlInitParser();
+    htmlInitAutoClose();
     xmlSetGenericErrorFunc(NULL, xmlFuzzErrorFunc);
 
     return 0;