Add constants used by getrandom linux syscall

getrandom syscall was added in kernel 3.17. Musl and android seems to use old kernel headers, but considering that they define SYS_getrandom, the constants GRND_NONBLOCK and GRND_RANDOM should also be defined.

Compile an empty library on wasm32 non-Emscripten

In preparation for eventually having a non-Emscripten based wasm32 target, this
commit makes `libc` the crate an empty library on wasm32 targets that are not
with `target_os = "emscripten"`. This may eventually get filled out over time,
but for now it's all empty!

In preparation for eventually having a non-Emscripten based wasm32 target, this
commit makes `libc` the crate an empty library on wasm32 targets that are not
with `target_os = "emscripten"`. This may eventually get filled out over time,
but for now it's all empty!

Fix sparc64-unknown-linux-gnu tests

Run sparc64 test in qemu system like s390x. Fix O_TMPFILE const.

Fixes https://github.com/rust-lang/libc/issues/822

Run s390x tests on qemu system

qemu in user mode cannot run binaries produced by rustc (it hangs), so we run the tests in a fully virtualized s390x machine using qemu-system-s390x.

Some constants had to be fixed.

Add WCONTINUED const for OpenBSD

Simple addition of `WCONTINUED` for OpenBSD-like systems. Built nix against this modified libc and used it to test.

Bump to 0.2.33

Just bumping the release to make getprotobyname, getprotobynumber and getservbyname available.

Fixes and test for x86_64-unknown-linux-gnux32

This fixes all libc tests and almost all rustc tests (3 libstd tests and one run-pass test fails).

Fixes https://github.com/rust-lang/libc/issues/816https://github.com/rust-lang/libc/issues/816

Add sparc64-unknown-linux-gnu to CI (with disabled tests)

Tests are disabled because qemu segfaults, see https://github.com/rust-lang/libc/issues/822

The builder is still useful to catch some errors.

Add mips64el to CI

Add powerpc64le to CI

Fix android ci

Fix kqueue filter consts type on NetBSD [WAS: Provide EV_SET]

Using BSD kqueue's `kevent` structure is tedious, because some BSD variants define the structure slightly differently. This forces user's code to differentiate between BSD variants and initialize `kevent` accordingly, which is annoying and error-prone.

For an example, refer to [MIO](https://github.com/carllerche/mio/blob/master/src/sys/unix/kqueue.rs#L38).

This is an attempt to fix it - provide a ctor function with the same signature across BSD variants.

Is an `impl` piece for a C structure allowed in libc?

**edit:** I noticed the `kevent` function has a similar problem, maybe I should include a fix for that too...
**edit:** ^ Done

fix ABI breakage in syscall constants

Fix other platforms impacted by 9029cfb9

Initial fixes for linux x32

Tested with a local build of rustc. The main test can be compiled but fails to execute (receives SIGTRAP, which I think in this case indicates memory violation, I will open an issue in the rustc repo).

This PR is important because it fixes the definition of `c_long` and `c_ulong`. Without these fixes, rustc crash with the error:

```
Cannot emit physreg copy instruction
UNREACHABLE executed at /checkout/src/llvm/lib/Target/X86/X86InstrInfo.cpp:5778!
```

Related https://github.com/rust-lang/rust/issues/37976

SYS_* constants are of type long in Android

The SYS_* constants should be `c_long` as `syscall` expect a `c_long` as first argument and in Android headers, there is no sign that these constants should be `unsigned long`.

So the compilation targeting ARM Android fails for dependent crates using `syscall`.

Introduce pthread_cancel() for terminating threads

pthread_cancel() is safer way to terminate thread than pthread_kill().

This function can be found from ISO/IEC 9945-1:1996 (“POSIX.1”) and first introduced into Single Unix Specification version 2 on 1997.

add setfsgid/setfsuid on Linux

Add BOTHER & termios2 to Android & Linux

This should be the same for both the struct and the constant across all Linux/Android platforms, but we'll see!