False positives with atoi, strtoull, if_nametoindex, syscall and possibly others
Examples to reproduce, tested on Debian stable/testing/sid
dehe-atoi.c:
```
#include <stdlib.h>
int main(int ac __attribute__((unused)),char **av) {
return atoi(av[1]);
}
```
dehe-if_nametoindex.c
```
#include <net/if.h>
int main(int ac __attribute__((unused)),char **av) {
return if_nametoindex(av[1]);
}
```
dehe-strtoull.c
```
#include <stdlib.h>
int main(int ac __attribute__((unused)),char **av) {
char *t;
return strtoull(av[1],&t,10);
}
```
dehe-syscall.c
```
#include <unistd.h>
int main(void) {
return syscall(0,0,0);
}
```
Output of deheader
deheader: remove <stdlib.h> from ./dehe-atoi.c
deheader: remove <net/if.h> from ./dehe-if_nametoindex.c
deheader: remove <stdlib.h> from ./dehe-strtoull.c
deheader: remove <unistd.h> from ./dehe-syscall.c
deheader: saw 4 files, 4 includes, 4 removable
issue