2. Write a void function named setTo5 that initializes the value of an
int variable used in the calling program to 5. Here's a framework for
a main program in which setTo5 is used: 
  #include <stdio.h>
  int main ( ) {
      int n = 27;
      setTo5 (/* an appropriate argument goes here */);
      printf ("n = %d\n", n);  /* should print n = 5 */
      return 0;
  }