Remove next() on backtrack (#441)

When trying to parse expression like:
```cpp
(:() = 0) as t;
```

`parameter_declaration_list()` fail to succed which is expected but
skips one symbol ('(') on returning that makes parser fail to process
expression succesfully.

Author: filipsajdak

source/parse.h

@@ -5610,7 +5610,6 @@ class parser
             else {
                 error("invalid parameter list", true, {}, true);
             }
-            next();
             return {};
         }