Prerequisites to build libc-test on Solaris

These changes are required as a first step to Solaris CI.

With these changes there are no "undeclared"
errors for libc-test on Solaris anymore.

fflags_t is not commonly defined on Solaris or illumos.

futimes is not commonly defined on Solaris, but futimesat is.

Several fixes for DragonFly

With these changes in place, crate "nix" works (with some patches applied).

This was not caught by libc-test, as checks for the execv functions
are disabled.

Add errno getter for Android

Separate and Update Fuchsia

The first commit pulls Fuchsia out into its own directory, while the second commit updates the "open" flags as in #848.

cc @smklein, @alexcrichton

Add aarch64 support to newlib bindings

It's all in the title. I grabbed the definition from  a small test in with a gcc toolchain, I hope it's correct.

There's currently no tests around newlib in the CI. Would it be possible to add them ? If so, how ?

Add syscall table for Linux sparc64

Use more convenient and UNIX-agnostic shebang

Pure sh scripts should use /bin/sh as it's available on every platform.

When using bash-specific features, use env to find it, as bash can
be installed in different places according the OS.

Pure sh scripts should use /bin/sh as it's available on every platform.

When using bash-specific features, use env to find it, as bash can
be installed in different places according the OS.

Add dyld functions and related types

r? @alexcrichton

Add dl_iterate_phdr and related types

A lot of this is more broadly supported than just Linux, but support for
those can be added later.

r? @alexcrichton

A lot of this is more broadly supported than just Linux, but support for
those can be added later.

Add network interface flag constants for all platforms

Add network interface flag constants for all platforms.

old PR: https://github.com/rust-lang/libc/pull/839

This reverts commit c124acba.

Add network interface flag constants for all platforms.

Expose MFD_ constants on all Linux targets.

These aren't exposed on non-MIPS musl targets, but since they're
part of a kernel API, they're still applicable, so we just don't
test them there but expose them anyways.

These aren't exposed on non-MIPS musl targets, but since they're
part of a kernel API, they're still applicable, so we just don't
test them there but expose them anyways.

Add SHM_ANON for FreeBSD

This is a constant for `shm_open` that is used instead of the address to create an anonymous shared memory mapping.

https://github.com/freebsd/freebsd/blob/a9656e45a9d1cc0fc5343dd941106e0b823ff770/sys/sys/mman.h#L168