Enusre that `no_core` is turned on, and while here update the `no_std`
header to be unconditionally applied.

Closes #1267

Expose IPV6_FLOWINFO* on Linux

Test that targets without a shipping libcore / libstd build properly

This PR tests that `libc` builds on targets that currently don't ship a `libcore`/`libstd` by cross-compiling to them from Linux and MacOSX using `Xargo`.

This fixes the build on DragonflyBSD (superseeds #1237), Haiku, bitrig, and OpenBSD (superseeds #1259).

cc @asomers @strangelittlemonkey @semarie

Add AF_ALG constants and structures

This reverts commit ae2663a7.

Moved inotify declarations up so that it works on android too.

Following my previous pull request to include inotify bindings, I would like to move the code so that it benefits android too.

Moved inotify_rm_watch out of the generic notbsd target and into specific linux and android targets because the second argument has a different type in android and linux.