Fixed #2612 (segmentation fault of cppcheck ( <><< ))

lib/tokenize.cpp

@@ -2057,7 +2057,7 @@ bool Tokenizer::tokenize(std::istream &code,
             {
                 tok->str(tok->str() + c2);
                 tok->deleteNext();
-                if (c1 == '<' && tok->next()->str() == "=")
+                if (c1 == '<' && Token::simpleMatch(tok->next(), "="))
                 {
                     tok->str("<<=");
                     tok->deleteNext();

test/testtokenize.cpp

@@ -49,6 +49,7 @@ private:
         TEST_CASE(tokenize13);  // bailout if the code contains "@" - that is not handled well.
         TEST_CASE(tokenize14);  // tokenize "0X10" => 16
         TEST_CASE(tokenize15);  // tokenize ".123"
+        TEST_CASE(tokenize16);  // #2612 - segfault for "<><<"
 
         // don't freak out when the syntax is wrong
         TEST_CASE(wrong_syntax);
@@ -516,6 +517,12 @@ private:
         ASSERT_EQUALS("0.125", tokenizeAndStringify(".125"));
     }
 
+    // #2612 - segfault for "<><<"
+    void tokenize16()
+    {
+        tokenizeAndStringify("<><<");
+    }
+
     void wrong_syntax()
     {
         {