This change fixes two issues.  First, the current cfmakeraw()
implementation in this crate appears to be making a stack copy of the
input "struct termios" before modifying it, rather than correctly
modifying the original through the pointer.  Before this modification
the routine did not, thus, set the flags for raw mode.

Second, we address the default settings of the MIN and TIME terminal
options.  On at least FreeBSD and Linux systems, the modern default
value for MIN appears to be 1; i.e., block and wait for at least one
input byte.  On most Solaris and illumos systems, the MIN control
character slot overlaps with EOF, and thus has a default value of 4.
This breaks at least the examples in the "termion" crate, and probably
quite a lot of other software written first and foremost for Linux
systems.  We need to force the MIN value to 1 while switching to raw
mode.

 * Function futimes is not available in Haiku.
 * Functions futimens and utimensat are.
 * Cleanup some leftover cfg_attr attributes.

Fix #1631

This is a Linux-only feature that was already present as a
syscall. Add it just to linux/gnu for the moment, as the musl version
bundled in the Rust's x86_64-unknown-linux-musl toolchain doesn't
include it yet.

Signed-off-by: Sergio Lopez <slp@redhat.com>

References:
* NetBSD (became available with 8.0):
  http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/sys/socket.h?annotate=1.129&only_with_tag=MAIN
  http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/sys/accept4.c?annotate=1.2&only_with_tag=MAIN
* Illumos:
  https://illumos.org/man/3socket/accept
  https://github.com/illumos/illumos-gate/blob/master/usr/src/uts/common/sys/socket.h
  https://github.com/illumos/illumos-gate/blob/master/usr/src/lib/libsocket/socket/weaks.c
* Solaris:
  https://docs.oracle.com/cd/E88353_01/html/E37843/accept-3c.html

Add AT_EACCESS to Linux, Solaris, and Fuchsia.

Add AT_SYMLINK_FOLLOW, AT_REMOVEDIR, and  _AT_TRIGGER to Solaris.

https://github.com/apple/darwin-xnu/blob/master/bsd/sys/mount.h#L288

Constants for the linux nfqueue netlink protocol (userspace firewall).

Continuation of #1562 and #1571.

fix #1633

Ref: https://android.googlesource.com/platform/bionic/+/refs/tags/ndk-r20/libc/include/sys/ucontext.h

Ref: https://android.googlesource.com/platform/bionic/+/refs/tags/ndk-r20/libc/include/sys/ucontext.h

Ref: https://android.googlesource.com/platform/bionic/+/refs/tags/ndk-r20/libc/include/sys/ucontext.h