RFR(xxxs): 8182034: os::Posix::is_valid_signal() should, if it uses sigaddset, initialize the signal set

[Thomas Stüfe]

Hi all,

May I please have a review and a sponsor for this very tiny fix. Kim Barret
found this while reviewing "8181503: Can't compile hotspot with c++11".

We are using sigaddset() to find out if a given signal number is a valid
signal number. The signal set used was not initialized probably. This never
led to an error (the function in its current form is tested and used at SAP
for years) but it is still invalid according to Posix.

Bug: https://bugs.openjdk.java.net/browse/JDK-8182034
Webrev:
http://cr.openjdk.java.net/~stuefe/webrevs/8182034-os-posix-is_valid_signal-sigemptyset/webrev.00/webrev/

Thanks and Kind Regards, Thomas