Update the FreeBSD CI image

As per #948 and #799 the FreeBSD CI qemu image needs to be updated to FreeBSD 11. I have done this and updated the README with the detailed steps taken. The new image is available for download at: http://bsd-ci.com/FreeBSD-11.1-RELEASE-amd64.qcow2.xz

redefine pthread_t for l4re-uclibc

Add ___errno() for Solaris

Edit documentation

Add sparc64-unknown-linux-gnu and x86_64-sun-solaris.
Remove aarch64-unknown-linux-musl.

Add sparc64-unknown-linux-gnu and x86_64-sun-solaris.
Remove aarch64-unknown-linux-musl.

Retract ucred type alias for sockpeercred from OpenBSD and Bitrig

Introduced in [this](https://github.com/rust-lang/libc/pull/941) PR.

Arguments of pledge(2) changed.

The arguments of pledge(2) have changed. However, the changes have to yet been propagated to Bitrig.

https://marc.info/?l=openbsd-tech&m=151268831628549&w=2

Recycle IFF_NOTRAILERS into IFF_STATICARP in OpenBSD but not in Bitrig.

https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/sys/net/if.h?rev=1.190&content-type=text/x-cvsweb-markup

getpwent_r() and getgrent_r() doesn't exist in OpenBSD and Bitrig

https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/sys/net/if.h?rev=1.190&content-type=text/x-cvsweb-markup

https://marc.info/?l=openbsd-tech&m=151268831628549&w=2

Added ucred (sockpeercred) for OpenBSD and Bitrig

OpenBSD and Bitrig has `struct ucred`implemented in the way it is used in `getsockopt(2)` with `SOL_SOCKET` and `SO_PEERCRED`. However, it is called `struct sockpeercred`.

Source: https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/sys/sys/socket.h?rev=1.65&content-type=text/x-cvsweb-markup

I added a type alias for `ucred` to enable Linux compatibility, but I'm not sure this is the correct way to do it.

Add FreeBSD `get[pw|gr]ent_r`, forgotten in #934

Sorry, accidentally forgot this when submitting #934..

Sorry, accidentally forgot this when submitting #934..

Add passwd/group APIs needed for nix-rust/nix#864

Hope I did this right. I only added platforms I could personally test. . .

cc: @gnzlbg

Use pre-ino64 FreeBSD symbols to resolve binary compatibility.

This follows the same method as other platforms like OSX and NetBSD.

This will fix rustup and building from git (once libc is updated for bootstrap)
on FreeBSD12 post-ino64 in https://github.com/freebsd/freebsd/commit/f713b08c027de35b0b8ed9990eabc32e100bee7a.
It also avoids having to hotpatch the stage0 compiler, and HOME/.cargo
libc files on FreeBSD12 to build rust.

The only real pitfall is that this will prevent interaction with inodes that
have an ino_t above the 32-bit limit due to truncation.  On the other hand
Rust won't work at all on 12 without doing this currently.  In general
it should not be a problem for users and if they need 64-bit ino_t they
can use a patched libc, rather than the current state of affairs in
requiring a patched libc to use Rust on 12.

A better, or complementary, approach would be something like proposed in
https://github.com/rust-lang/rfcs/pull/2048 to allow targetting a specific
version of FreeBSD. This would allow Rust to default to this compatibility
mode by targetting FreeBSD10 and still allow targetting FreeBSD12 for 64-bit
ino_t.

The symbol versions used were taken from the old version in
https://github.com/freebsd/freebsd/commit/f713b08c027de35b0b8ed9990eabc32e100bee7a#diff-61a32fcfb7ecd4517665fed591813c57
and
https://github.com/freebsd/freebsd/commit/f713b08c027de35b0b8ed9990eabc32e100bee7a#diff-7f67ccf8b5f44ff2f54eaab0207abb8d.

The scope of functions versioned here differs from other platforms as
not all structs were modified that were on others, such as DIR for
`opendir`, `telldir`, etc.  Only functions using dirent, stat, glob_t,
and dev_t need the changes.

Fixes https://github.com/rust-lang/rust/issues/42681

This follows the same method as other platforms like OSX and NetBSD.

This will fix rustup and building from git (once libc is updated for bootstrap)
on FreeBSD12 post-ino64 in https://github.com/freebsd/freebsd/commit/f713b08c027de35b0b8ed9990eabc32e100bee7a.
It also avoids having to hotpatch the stage0 compiler, and HOME/.cargo
libc files on FreeBSD12 to build rust.

The only real pitfall is that this will prevent interaction with inodes that
have an ino_t above the 32-bit limit due to truncation.  On the other hand
Rust won't work at all on 12 without doing this currently.  In general
it should not be a problem for users and if they need 64-bit ino_t they
can use a patched libc, rather than the current state of affairs in
requiring a patched libc to use Rust on 12.

A better, or complementary, approach would be something like proposed in
https://github.com/rust-lang/rfcs/pull/2048 to allow targetting a specific
version of FreeBSD. This would allow Rust to default to this compatibility
mode by targetting FreeBSD10 and still allow targetting FreeBSD12 for 64-bit
ino_t.

The symbol versions used were taken from the old version in
https://github.com/freebsd/freebsd/commit/f713b08c027de35b0b8ed9990eabc32e100bee7a#diff-61a32fcfb7ecd4517665fed591813c57
and
https://github.com/freebsd/freebsd/commit/f713b08c027de35b0b8ed9990eabc32e100bee7a#diff-7f67ccf8b5f44ff2f54eaab0207abb8d.

The scope of functions versioned here differs from other platforms as
not all structs were modified that were on others, such as DIR for
`opendir`, `telldir`, etc.  Only functions using dirent, stat, glob_t,
and dev_t need the changes.

Fixes https://github.com/rust-lang/rust/issues/42681

Link against kevent@FBSD_1.0 to fix ABI compat with FreeBSD12.

struct kevent was modified in FreeBSD12.  The @FBSD_1.0 symbol supports the old
structure ABI still.

This allows the `mio` crate tests to now pass on FreeBSD12.

struct kevent was modified in FreeBSD12.  The @FBSD_1.0 symbol supports the old
structure ABI still.

This allows the `mio` crate tests to now pass on FreeBSD12.

Add Solaris constants needed by net2

The added constants are
IPV6_UNICAST_HOPS,
IPV6_MULTICAST_IF,
IPV6_MULTICAST_HOPS,
IP_MULTICAST_IF.

The added constants are
IPV6_UNICAST_HOPS,
IPV6_MULTICAST_IF,
IPV6_MULTICAST_HOPS,
IP_MULTICAST_IF.

Add IPV6_UNICAST_HOPS to fuchsia module

Recent change #925 added constants for IPV6 multicast, but seems to have inadvertently left off IPV6_UNICAST_HOPS from the fuchsia module.

Fixes #932