- Copy 17 functions definitions from src/unix/mod.rs
      to src/unix/bsd/mod.rs src/unix/haiku/mod.rs
      src/unix/notbsd/linux/mod.rs and src/unix/solaris/mod.rs
    - Add some functions to android that was cfged out
    - Remove cf* and tc* functions implementations for android
      (they are available with api >= 12, which was release in 2011)

This includes implementations for Android.

- some tests are failing
- remove readlink, timegm and sig* functions in favor of the
  unix/mod.rs definitions
- remove time64_t (it is not defined for aarch64)
- move some definitions to android/b32.rs and create appropriated
  definitions in android/b64.rs

I'm unsure of whether there is support in OS X for this, and I can't find
anything online (I'm betting there isn't), but I'm going to let this run
through CI to confirm

Apparently a lot of libc's don't put "const" on the return type for
readdir, which causes type mismatch.

The readdir_r call has problems, and we'll probably want to move to
readdir on many, if not most, unix targets. This patch makes readdir
available in unix, rather than just solaris as before.

See https://github.com/rust-lang/rust/issues/40021

Having the B* constants in `unix/notbsd/mod.rs` passed CI tests
except for powerpc.  So we'll try moving into individual
arch/ABI that the CI tests cover for now. This commit should
pass for the following:

- mips32
- mips64
- musl32
- musl64
- android32
- android64
- arm32
- aarch64
- x86
- x86_64

Then we can figure out the powerpc variants.  This also prevents
potential errors for sparc64 which is not covered by CI.

For compatibility reasons, Solaris historically had its header files
setup so that, unless specifically requested through specific header
defines, either the old pre-POSIX interfaces or POSIX.1c Draft 6
interfaces were used. However, in the case of rust, since these symbols
are linked directly instead of via system header files, the underlying
posix symbol name can be used directly instead.

These definitions should be corrected to match what they do on almost
every other platform.

Be aware this is a breaking change in terms of interface for any crates
/ consumers of these interfaces for Solaris.

Fixes #522