Set rustup profile to minimal on Windows

Minor clean-up CI docs

Bump version to 0.2.69

Enable `wasm32-unknown-emscripten` target on CI

Remove license headers

Add bindings for POSIX regexes

Headers I used:

Oh, for reference, here are the headers I used while working on this:

- musl: https://git.musl-libc.org/cgit/musl/tree/include/regex.h?id=8327ae0cb23b799bc55a45e0d4bd95f5a2b1cdf1
- glibc: https://sourceware.org/git/?p=glibc.git;a=blob;f=posix/regex.h;h=87cce7f5cb8cc3b678467329b479bd511e250e61;hb=HEAD
- macOS: https://opensource.apple.com/source/Libc/Libc-997.90.3/include/regex.h.auto.html
- FreeBSD: https://github.com/freebsd/freebsd/blob/8103b0ddb041617b7cd161528f0ff93ff32970a2/include/regex.h
- NetBSD: https://github.com/NetBSD/src/blob/61c8f6fbb7e38b20e862d5cb3ed2203312963283/include/regex.h

unix: add strndup()

Add strndup(), as specified by POSIX.1-2008.

Run rustfmt

Split up Solaris and illumos targets

Add definition of ucontext_t for aarch64-unknown-linux-gnu

Add defines for HUGETLB size - solves #1700

This adds the defines from include/uapi/asm-generic/hugetlb_encode.h and the corresponding defines in include/uapi/linux/mman.h to linux_like/linux/gnu/mod.rs and the equivalent for musl in linux_like/linux/musl/mod.rs

Solves #1700

Removes two defines from musl/b32/hexagon.rs that are now provided two mudules "up"

Add strsignal(3) to unix

Use fork ctest until the maintainer gets back

This does not add sys_siglist because the docs specify that the function
should be used instead, whenever possible.

Add Linux UDP constants

Update freebsd 12 image

fix cfmakeraw() for illumos and Solaris