explicit casting for const

```c++
#include <iostream>
#include <limits.h>

int main (int argc, char *argv[]) {
  const int a = 10;
  int *p = (int *)&a;
  return 0;
}
``` 
give 
```c++
#include <iostream>
#include <limits.h>

int main(int argc, char ** argv)
{
  const int a = 10;
  int * p = static_cast<int *>(&a);
  return 0;
}
``` 
