statx using the musl libc

[famfo]

Since musl 1.2.5 it supports the statx() syscall: https://git.musl-libc.org/cgit/musl/tree/WHATSNEW?h=v1.2.5#n2402 defined here: https://git.musl-libc.org/cgit/musl/tree/src/linux/statx.c?h=v1.2.5

target triple: *-unknown-linux-musl