FreeBSD: machine register structs

Add constants and eventfd to illumos

linux hexagon: add missing defines

This commit defines ETIMEDOUT, SIGSTKSZ, MINSIGSTKSZ

Use ctest2 to drop old dependencies

Add `ip_mreqn` on musl targets

FreeBSD: Follow upstream `WIFSIGNALED` change

Change branch specification

remove SmartOS constants not applicable to illumos or Solaris

SmartOS is a downstream distribution of illumos, and carries a number of
additional patches that are not commonly available in other illumos
distributions.  They are also not found in Oracle Solaris.  With these
removed, the libc tests pass on a stock illumos system running
OpenIndiana.

Bump version to 0.2.71

Add `llvm-tools` component

Import `core::ops` to use `Range` syntax

This is required on rust-lang/rust.

Add types for newlib on Xtensa.

Add `TCP_KEEP{INTVL,CNT}` to macOS

linux: ptrace: Add definition for PTRACE_SYSEMU/_SINGLESTEP

Update FIXME comment

Deprecate `KERN_USERMOUNT` and `KERN_ARND` in 0.2.71

Re-define `__priority_which`s as c_uint in linux-gnu

[FreeBSD] Add missing getnameinfo() flag values.

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>