8233989: Create an IPv4 version of java/net/MulticastSocket/SetLoopbackMode.java
Summary: This fix adds an IPv4 version of test SetLoopbackMode.java that calls SetLoopbackMode in IPv4 only mode, and runs only if IPv4 is enabled.
Reviewed-by: dfuchs
^build/
^dist/
^.idea/
nbproject/private/
^webrev
^.src-rev$
^.jib/
(^|/)\.DS_Store
(^|/)\.metadata/
(^|/)\.recommenders/
test/nashorn/script/external
test/nashorn/lib
NashornProfile.txt
(^|/)JTreport/
(^|/)JTwork/
(^|/)\.git/
^src/utils/hsdis/build/