`statx` should be available on more platform/architecture

[oxalica]

Including struct statx, fn statx, const SYS_statx, sub-structs and related flags used by them.

Currently, SYS_statx is missing on gnu with arch mips, aarch64, mips64, s390x.
And all of them are missing on musl, while it seems to support them already.

Syscall id is only architecture related. Maybe be can simply get them from here ?

[oxalica]

Related: rust-lang/rust#65094