Warning when compiling seccomp-run.c on recent distributions

```
make
gcc src/seccomp-run.c -o src/seccomp-run
src/seccomp-run.c:61: warning: "PATH_MAX" redefined
   61 | #define PATH_MAX 2048
      |
In file included from src/seccomp-run.c:42:
/usr/include/linux/limits.h:13: note: this is the location of the previous definition
   13 | #define PATH_MAX        4096    /* # chars in a path name including nul */
```