Fix #14918: fuzzing crash (stack-overflow) in findTokensSkipDeadCodeImpl() (#8732)

Co-authored-by: Daniel Marjamäki <daniel.marjamaki@gmail.com>

Author: ludviggunne

lib/tokenize.cpp

@@ -8814,6 +8814,9 @@ void Tokenizer::findGarbageCode() const
             if (!cpp || mSettings.standards.cpp < Standards::CPP20 || !Token::Match(tok->previous(), "%name% : %num% ="))
                 syntaxError(tok, tok->strAt(1) + " " + tok->strAt(2));
         }
+        else if (!cpp && Token::Match(tok, "++|-- ++|--")) {
+            syntaxError(tok, tok->str() + tok->strAt(1));
+        }
         else if (Token::simpleMatch(tok, ") return") && !Token::Match(tok->link()->previous(), "if|while|for (")) {
             if (tok->link()->previous() && tok->link()->previous()->isUpperCaseName())
                 unknownMacroError(tok->link()->previous());

test/cli/fuzz-crash_c/crash-9feb09f580c0cf101456c6c650ab4193b1009d07

@@ -0,0 +1 @@
+d(){e?&d=d++++F:a}