Merge branch 'xmlregexp-critical' into 'master'

xmlregexp: Add check for exec->state when creating xmlRegExec object

See merge request GNOME/libxml2!245

xmlregexp.c

@@ -3610,6 +3610,8 @@ xmlRegNewExecCtxt(xmlRegexpPtr comp, xmlRegExecCallbacks callback, void *data) {
     exec->comp = comp;
     if (comp->compact == NULL)
 	exec->state = comp->states[0];
+    if (exec->state == NULL)
+	return(NULL);
     exec->transno = 0;
     exec->transcount = 0;
     exec->callback = callback;