Serial Experiments GitHub Actions

Let's start the party to close #1582.

BuildChannelsMacOS, SemverLinux, and SemverMacOS

StyleAndDocs, BuildChannelsLinux, and DockerSwitch

Fix {aarch64,arm}-android targets' CI

Android: Add VMADDR_ constants.

pthread_getattr_np is not present on illumos

Fix bootstrap on redox

Avoid attempting to enable the static_nobundle feature twice, which
results in rustc error E0636.

Add more constants for Linux like OS

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

Add SYS_pidfd_open and SYS_clone3

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>