[8u] RFR: 8132376: Add @requires os.family to the client tests with access to internal OS-specific API

[Alex Kashchenko]

Hi,

Please review the backport of JDK-8132376 to 8u.

Bug: https://bugs.openjdk.java.net/browse/JDK-8132376

9 commit: http://hg.openjdk.java.net/jdk9/jdk9/jdk/rev/3aef124b3176

8u-dev webrev: http://cr.openjdk.java.net/~akasko/jdk8u/8132376/webrev.00/

This change introduces two new Windows-specific tests. 8u patch removes 
@modules jtreg tag, and adds a type cast to getPeer() call [1][2], that 
is necessary due to changes introduced in 9 with JDK-8074028.

Testing: checked that new tests pass on Windows. Checked that tests 
marked with "@requires (os.family == "mac")" are selected on macOS.


[1] http://hg.openjdk.java.net/jdk9/jdk9/jdk/rev/3aef124b3176#l2.73
[2] http://hg.openjdk.java.net/jdk9/jdk9/jdk/rev/3aef124b3176#l3.76

-- 
-Alex