build_error: both 'short' and '_Bool' in declaration specifiers

## ERROR: 

```
In file included from exrecover.c:106:
ex.h:194:17: error: both ‘short’ and ‘_Bool’ in declaration specifiers
  194 | typedef short   bool;
```

## Steps to Reproduce:
* build the master branch
```
make
```

## Possible solution:
* why not just import `stdbool.h`