tokenize.cpp: fixed fuzzing crash in setScopeInfo() (#6092)

Co-authored-by: chrchr-github <chrchr-github@users.noreply.github.com>

Author: firewave

lib/tokenize.cpp

@@ -1253,10 +1253,9 @@ void Tokenizer::simplifyTypedefCpp()
         Token *namespaceEnd = nullptr;
 
         // check for invalid input
-        if (!tokOffset)
+        if (!tokOffset || tokOffset->isControlFlowKeyword())
             syntaxError(tok);
 
-
         if (tokOffset->str() == "::") {
             typeStart = tokOffset;
             tokOffset = tokOffset->next();

test/cli/fuzz-crash/crash-5db88ae1610f5a9782ea78af206f9cd87b6708dd

@@ -0,0 +1 @@
+{for(typedef;);}