syscalls: align argument names for m68k and i386 with canonical definitions

[Yudis-bit]

Problem

In Kafel, argument names are part of the policy syntax. Inconsistencies across architecture tables break cross-compilation of portable policies.

For example, the following valid policy compiles on amd64 and aarch64, but currently fails on i386 and m68k:

POLICY sample {
  ALLOW {
    statx { statxbuf != NULL },
    setxattrat { dfd == AT_FDCWD }
  }
}

• On i386: fails with unknown argument statxbuf (table had buffer).
• On m68k: fails with unknown argument dfd (table had dirfd).

Changes

Align i386 and m68k syscall argument definitions with generic Linux UAPI (asm-generic/unistd.h) and other architecture tables in src/syscalls/:

1. i386 (src/syscalls/i386_syscalls.c)

   • statx: buffer -> statxbuf (ARG_4)

2. m68k (src/syscalls/m68k_syscalls.c)

   • fsopen: _fs_name -> fs_name (ARG_0)
   • fsconfig: _key, _value -> key, value (ARG_2, ARG_3)
   • setxattrat, getxattrat, listxattrat, removexattrat, open_tree_attr, file_getattr, file_setattr: dirfd -> dfd (ARG_0)

Verification

• Confirmed argument identifiers against Linux UAPI headers (include/uapi/asm-generic/unistd.h, include/uapi/linux/fs.h).
• Verified build and test suite pass cleanly:

  make clean && make test