dirtyfrag (exploit compilation/exploitability)

Howdy,

I'm testing this on CentOS 7.9 and the code fails to compile. Does this indicate that EL7 isn't exploitable by Dirty Frag, like Copy Fail? Or is this just an issue with the code not supporting such an old distro, kernel and compiler?

```shell
$ cat /etc/redhat-release ; uname -r; gcc --version

CentOS Linux release 7.9.2009 (Core)
3.10.0-1160.119.1.el7.x86_64
gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-44)
```

```shell
$ gcc -I/usr/src/kernels/3.10.0-1160.119.1.el7.x86_64/include \
> -I/usr/src/kernels/3.10.0-1160.119.1.el7.x86_64/arch/x86/include \
> -I/usr/src/kernels/3.10.0-1160.119.1.el7.x86_64/arch/x86/include/generated \
> -O0 -Wall -o exp exp.c -lutil
In file included from /usr/include/bits/fcntl-linux.h:323:0,
from /usr/include/bits/fcntl.h:61,
from /usr/include/fcntl.h:35,
from exp.c:7:
/usr/src/kernels/3.10.0-1160.119.1.el7.x86_64/include/linux/falloc.h:12:2: error: unknown type name ‘__s16’
__s16 l_type;
^
/usr/src/kernels/3.10.0-1160.119.1.el7.x86_64/include/linux/falloc.h:13:2: error: unknown type name ‘__s16’
__s16 l_whence;
^
/usr/src/kernels/3.10.0-1160.119.1.el7.x86_64/include/linux/falloc.h:14:2: error: unknown type name ‘__s64’
__s64 l_start;
^

...

exp.c:1896:1: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘{’ token
{
^
In file included from /usr/src/kernels/3.10.0-1160.119.1.el7.x86_64/include/linux/skbuff.h:17:0,
from /usr/src/kernels...