RFR: 8129526: Solaris: clean up another remnant of interruptible I/O

[David Holmes]

bug: https://bugs.openjdk.java.net/browse/JDK-8129526
webrev: http://cr.openjdk.java.net/~dholmes/8129526/webrev/

Nothing but code deletion here :)

Interruptible I/O was finally removed some time ago but we found a 
remnant left over in the Solaris code in the use of SIGinterrupt. But 
without interruptible I/O we don't need SIGinterrupt, nor its 
cross-platform alter-ego INTERRUPT_SIGNAL. Some code related to 
INTERRUPT_SIGNAL was copied from the Solaris code to the Linux code 
(even though interruptible I/O never existed on linux) and it was later 
copied from the Linux code to BSD and AIX. All of that has now been 
cleaned up too - hence the cc to porters-dev to make sure the AIX folk 
see this.

Testing: JPRT

Thanks,
David