int make_friends(const char *name1, const char *name2, User *head) {
    User *curr = head;
    User *user1 = NULL;
    User *user2 = NULL;
    int found_zero = 1;
    //traverses through list, assigns curr to user 1 and user2
    if(strcmp(name1, name2)==0){
        return 3;
    }
    else{
        while(curr != NULL){
            if(strcmp(curr ->name, name1)==0 ){
                user1 = curr;
            }
            if(strcmp(curr ->name, name2)==0 ){
                user2 = curr;
            }
        curr= curr->next;
        }
        if(user1 == NULL ||  user2 ==NULL){
            return 4;
        }
        else{
            for(int x =0;x<MAX_FRIENDS;x++){
                if(strcmp(user1->friends[x]->name, name2)==0){
                    return 1;
                }
           }
            for(int i =0; i<MAX_FRIENDS; i++){
                if(user1->friends[i]==0){
                    user1->friends[i]= user2;
                    break;
                }
                else{
                    found_zero = 0;
                }
            }
            for(int j= 0;j<MAX_FRIENDS;j++){
                if(user2->friends[j]==0){
                    user2->friends[j]= user1;
                    break;
                }
                else{
                    found_zero = 0;
                }
            }
            if(found_zero ==0){
                return 2;
            }
            else{
            return 0;
            }
        }
    }
}
Make two users friends with each other.  This is symmetric. a pointer to each user must be stored in the 'friends' array of the other.
New friends must be added in the first 0 in the 'friends' array. Return 0 on success,1 if the two users are already friends,2 if the users are not already friends, but at least one already has MAX_FRIENDS friends, 3 if the same user is passed in twice,4 if at least one user does not exist.
 