Deprecate mach APIs: users should use the `mach` crate instead.

See #981, the mach APIs have breaking changes from MacOSX SDK release to release, and that's pretty much what the users are seeing here. We are currently not exposing that many `mach` APIs in `libc`, so this PR deprecates them, forwarding users to use the `mach` crate instead, which provides the mach user-space APIs, is tested against multiple SDK versions, handles removed/deprecated/breaking API changes/etc. Doing all of that in `libc` feels overkill.

Closes #981 .

Add powerpc64-unknown-freebsd target

Per https://github.com/rust-lang-nursery/stdsimd/pull/765 add powerpc64-unknown-freebsd to prevent further breakages.

Fix android SA_* constants

Trying to crosscompile wait-timeout to armv7-linux-androideabi I found that SA_* had different types in libc, but they have to be the same because they are used in bitwise operations.

Set the type for S_ISUID, S_ISGID and S_ISVTX correctly

Temporarily disable some solaris targets

 Move to LINUX_NO_CORE_TARGETS per gznlbg's suggestion.

Add final rtnetlink constants

This is a follow up to the PR #1351 which is for issue #1059 as it was closed before I realized there's one last set of netlink constants needed for use with rtnetlink. I'm marking this as WIP until I've verified everything's good with CI and that I've included all necessary constants. I'll remove WIP once it's passing CI and it's ready for review.

Change datatype for some IFF_ constants

These were originally added as c_short types, but all other IFF_ constants
are c_int. This commit changes them to match all the other constants for
consistency.

Closes #915

Move to RUST_NIGHTLY_LINUX_TARGETS per gznlbg's suggestion.

Deprecate `use_std` cargo feature: use `std` instead .

Related to #657 .

These were originally added as c_short types, but all other IFF_ constants
are c_int. This commit changes them to match all the other constants for
consistency.

Fix locale_t in unix and fuchsia.

Closes #1055.

Closes #1055.

Run CMSG tests on s390x

Closes #1240.

Closes #1240.

Closes #981 .

Related to #657 .

Fix Android build jobs