$ cargo build --target=aarch64-linux-android --features=std
   Compiling getrandom v0.3.0 (/Users/taiki/projects/forks/others/getrandom)
   Compiling cfg-if v1.0.0
error[E0432]: unresolved import `libc`
 --> src/backends/../util_libc.rs:6:13
  |
6 |         use libc::__errno as errno_location;
  |             ^^^^ use of unresolved module or unlinked crate `libc`
  |
  = help: if you wanted to use a crate named `libc`, use `cargo add libc` to add it to your `Cargo.toml`

error[E0433]: failed to resolve: use of unresolved module or unlinked crate `libc`
  --> src/backends/../util_libc.rs:68:47
   |
68 |                 if err.raw_os_error() != Some(libc::EINTR) {
   |                                               ^^^^ use of unresolved module or unlinked crate `libc`
   |
   = help: if you wanted to use a crate named `libc`, use `cargo add libc` to add it to your `Cargo.toml`

<ommited>

error[E0433]: failed to resolve: use of unresolved module or unlinked crate `libc`
   --> src/backends/use_file.rs:207:23
    |
207 |         let mut pfd = libc::pollfd {
    |                       ^^^^ use of unresolved module or unlinked crate `libc`
    |
    = help: if you wanted to use a crate named `libc`, use `cargo add libc` to add it to your `Cargo.toml`