Does not compile on arm64

[kylewillmon]

The rust-landlock crate does not compile on arm64. It fails with the following error:

error[E0425]: cannot find value `__NR_LANDLOCK_CREATE_RULESET` in this scope
Error:   --> /home/runner/.cargo/git/checkouts/rust-landlock-d80c47128915e4ea/1e09cb0/src/uapi/mod.rs:41:13
   |
41 |     syscall(__NR_LANDLOCK_CREATE_RULESET as i64, attr, size, flags) as c_int
   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not found in this scope

error[E0425]: cannot find value `__NR_LANDLOCK_ADD_RULE` in this scope
Error:   --> /home/runner/.cargo/git/checkouts/rust-landlock-d80c47128915e4ea/1e09cb0/src/uapi/mod.rs:47:13
   |
47 |     syscall(__NR_LANDLOCK_ADD_RULE as i64, ruleset_fd, rule_type, rule_attr, flags) as c_int
   |             ^^^^^^^^^^^^^^^^^^^^^^ not found in this scope

error[E0425]: cannot find value `__NR_LANDLOCK_RESTRICT_SELF` in this scope
Error:   --> /home/runner/.cargo/git/checkouts/rust-landlock-d80c47128915e4ea/1e09cb0/src/uapi/mod.rs:51:13
   |
51 |     syscall(__NR_LANDLOCK_RESTRICT_SELF as i64, ruleset_fd, flags) as c_int
   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^ not found in this scope

For more information about this error, try `rustc --explain E0425`.
error: could not compile `landlock` due to 3 previous errors

Here is a link to the code where it is clear that those constants are only defined for the x86_64 architecture.