adding new illumos ptsname_r call.

[devnexen]

while at it, fixing PTHREAD_MUTEX_DEFAULT which differs from solaris.

man page

[rustbot]

r? @tgross35

rustbot has assigned @tgross35. They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

[rustbot]

Some changes occurred in solarish module

cc @jclulow, @pfmooney

[devnexen]

@rustbot label stable-nominated

[tgross35]

The above change was reverted as suggested, @pfmooney does this now look reasonable to you?

Also @devnexen do you have links to relevant headers / manpages?

[devnexen]

description updated

[tgross35]

@pfmooney any chance you could double check this with the changes?

[tgross35]

This looks straightforward enough to me so I'll just merge it. I won't backport it for a few days at least, @pfmooney feel free to leave an ack/nack at any time.