1952: Update CI name; replace with GitHub Actions

`@lzutao` fixes #1952 , please test

Implement accept4 on Android as raw syscall.

This PR implements `accept4()` on Android using `syscall()` instead of the `accept4()` wrapper.

This is done because the `accept4()` wrapper wasn't added to Androids `libc` until version 5.0 (API level 21). By using `syscall` directly, `accept4` will also work on older  Android versions.

The kernel itself has supported it since Linux 2.6.28, which was shipped with stock Android since version 1.6 already: https://en.wikipedia.org/wiki/Android_version_history#Android_1.6_Donut_(API_4)

At the moment, the CI for the rust repo still uses API level 14. Although I also opened a PR to bump that too: https://github.com/rust-lang/rust/pull/78601. However, it might make sense to keep the old API level in CI if this is merged.

This avoids relying on Android 5.0 / API level 21. The Linux kernel used
by Android supports the syscall (except in truly ancient Android
versions), but the Android libc did not expose a wrapper.

Adding dl_iterate_phdr function to uclibc

Adding dl_iterate_phdr function and related structs and types to the
uclibc module as per the file include/link.h found in the uClibc-ng
repository as of version 1.0.36. This is necessary in order for rust to
work with a new target armv7-unknown-linux-uclibceabihf.

Adding dl_iterate_phdr function and related structs and types to the
uclibc module as per the file include/link.h found in the uClibc-ng
repository as of version 1.0.36. This is necessary in order for rust to
work with a new target armv7-unknown-linux-uclibceabihf.

Update to FreeBSD 12.2

https://www.freebsd.org/releases/12.2R/announce.html

Update GHA Ubuntu version to 20.04

Add more TCP options for solaris systems.

This adds the `TCP_KEEPCNT` and `TCP_KEEPINTVL` tcp values to the libc crate. It also corrects the value of `TCP_KEEPIDLE` for Solaris systems. As seen in the diff, the value is different between illumos and Solaris (as the feature was added after the two code bases forked, and each ended up choosing a different value).

Adding these to libc will allow the nix crate to utilize them when used on solarish systems.

Update redox socket constants

Add endservent, getservbyport, getservent, setservent

Rollup of 2 pull requests

Successful merges:

 - #1953 (Add dl_iterate_phdr to some BSD OSs)
 - #1960 (Disable `sparc-unknown-linux-gnu` for now)

Failed merges:

r? `@ghost`

Disable `sparc-unknown-linux-gnu` for now

Add dl_iterate_phdr to some BSD OSs

Add dl_iterate_phdr for freebsd, openbsd and netbsd: #1066
cc https://github.com/rust-lang/backtrace-rs/issues/325

* Include some header files
* Ingore tests for p_type field of `Elf*_Phdr` because of
  conflicting with p_type macro from resolve.h