This adds various WASI libc definitions to the Rust libc bindings that I
needed while porting some applications to WASI.

It also removes the `pause` binding since newer versions of WASI libc
have removed this function as well. (WASI currently has no syscall with
this functionality.)

Plus, add new constants for sysctls that give names to existing magic numbers.

https://reviews.freebsd.org/rS350749
https://reviews.freebsd.org/rS352486

It was picked up transitively on >10, but tests failed on 10

In particular:
Add timerfd constants and functions, from sys/timerfd.h.
Add EFD_SEMAPHORE and group all EFD_ constants together.
Add sigtimedwait function, from signal.h.
Add missing fallocate constants and functions, from linux/falloc.h and fcntl.h.
Add xattr functions, from sys/xattr.h.
Add SCHED_ and SEEK_ constants, from linux/sched.h and bits/seek_constants.h.
Add rlimit functions, from sys/resource.h.
Add RENAME_ constants, from stdio.h.
Add ino64_t type, from sys/types.h.

This patchs adds missing flag values for getnameinfo()
on FreeBSD, the following flags have been added from
the FreeBSD tree.

 /*
  * Flag values for getnameinfo()
  */
 #define	NI_NOFQDN	0x00000001
 #define	NI_NUMERICHOST	0x00000002
 #define	NI_NAMEREQD	0x00000004
 #define	NI_NUMERICSERV	0x00000008
 #define	NI_DGRAM	0x00000010
 #define	NI_NUMERICSCOPE	0x00000020

Signed-off-by: Valdemar Erk <valdemar@erk.io>

Headers I used:

Oh, for reference, here are the headers I used while working on this:

- musl: https://git.musl-libc.org/cgit/musl/tree/include/regex.h?id=8327ae0cb23b799bc55a45e0d4bd95f5a2b1cdf1
- glibc: https://sourceware.org/git/?p=glibc.git;a=blob;f=posix/regex.h;h=87cce7f5cb8cc3b678467329b479bd511e250e61;hb=HEAD
- macOS: https://opensource.apple.com/source/Libc/Libc-997.90.3/include/regex.h.auto.html
- FreeBSD: https://github.com/freebsd/freebsd/blob/8103b0ddb041617b7cd161528f0ff93ff32970a2/include/regex.h
- NetBSD: https://github.com/NetBSD/src/blob/61c8f6fbb7e38b20e862d5cb3ed2203312963283/include/regex.h

This adds the defines from include/uapi/asm-generic/hugetlb_encode.h and the corresponding defines in include/uapi/linux/mman.h to linux_like/linux/gnu/mod.rs and the equivalent for musl in linux_like/linux/musl/mod.rs

Solves #1700

Removes two defines from musl/b32/hexagon.rs that are now provided two mudules "up"

The `fanotify` API[0] is a linux-specific API for notification and interception
of filesystem events. In some ways it is similar to `inotify`, but with
different advantages/tradeoffs. It is particularly well suited to full
filesystem/mount monitoring (vs per directory) and for allowing/denying access
to files (`inotify` lacks this capability).

The `fanotify` API has been updated several times since it was enabled in Linux
2.6.37. Presently I've only included support for the original `fanotify`
features, and the `FAN_MARK_FILESYSTEM` addition made in Linux 4.20. There are
subsequent updates in 5.0 and 5.1 not covered in this initial commit.

This commit adds the relevant constants and types from
`uapi/linux/fanotify.h`[1] and two new functions (`fanotify_init`[2] and
`fanotify_wrap`[3]) to `src/unix/linux_like/linux/mod.rs`. While I believe this
API is also present on Android I have presently limited my attention to Linux.

Although this commit focuses on Linux 4.20.x's `fanotify` API/constants I have
skipped adding constants for `FAN_ALL_CLASS_BITS`, `FAN_ALL_INIT_FLAGS`,
`FAN_ALL_MARK_FLAGS`, `FAN_ALL_EVENTS`, `FAN_ALL_PERM_EVENTS` and
`FAN_ALL_OUTGOING_EVENTS` even though they are present in this kernel version's
headers. These defines were deprecated[4] in later releases with instructions to
not use them in new programs or extend them with new values. It would be a shame
for new Rust programs to use deprecated #defines!

[0]: http://man7.org/linux/man-pages/man7/fanotify.7.html
[1]: https://github.com/torvalds/linux/blob/d54f4fba889b205e9cd8239182ca5d27d0ac3bc2/include/uapi/linux/fanotify.h
[2]: http://man7.org/linux/man-pages/man2/fanotify_init.2.html
[3]: http://man7.org/linux/man-pages/man2/fanotify_mark.2.html
[4]: https://github.com/torvalds/linux/commit/23c9deeb3285d34fd243abb3d6b9f07db60c3cf4#diff-4c9ca62be6bf38cc08f7ea9daf16e379

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

Continuation of #1562 and #1571.

This triggers a warning on a recent nightly, which in turn breaks CI due to
`#![deny(warnings)]` in libc-test/build.rs

This commit performs a number of updates for libc with the `wasm32-wasi`
target:

* Updates the `wasi-libc` repository commit used (previously known as
  `wasi-sysroot`)
* Updates the container to Ubuntu 19.10 which has Clang 9 packaged which
  is all we need.
* Avoids building `wasmtime` and instead downloads a precompiled binary.
* Updates bindings in `src/wasi.rs` to match the current upstream state.

Modelled after the cmsg tests, this wraps the C macro into a function, and then
compares the results to the Rust implementation in libc.