pax: add <sys/sysmacros.h> for Linux

* On Arch Linux, the build failed, makedev(3) indicates
  #include <sys/sysmacros.h>
* On Debian Buster, the build succeed but a big warning is displayed:
    warning: In the GNU C Library, "minor" is defined
    by <sys/sysmacros.h>. For historical compatibility, it is
    currently defined by <sys/types.h> as well, but we plan to
    remove this soon. To use "minor", include <sys/sysmacros.h>
    directly. If you did not intend to use a system-defined macro
    "minor", you should undefine it after including <sys/types.h>.

(triaxx)