crypto/rand, internal/syscall/unix: add support for getrandom syscall on solaris
The getrandom syscall is available on Solaris and Illumos, see
https://docs.oracle.com/cd/E88353_01/html/E37841/getrandom-2.html and
https://illumos.org/man/2/getrandom
Change-Id: Id1c65d6a5b2fbc80d20b43d8b32dab137ca950ca
Reviewed-on: https://go-review.googlesource.com/c/go/+/299134
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>