Allows masking of interrupt flag if previously the flag is already set. Does nothing otherwise.
Typical use:
InterruptUtil interruptUtil = new InterruptUtil(context);
try {
interruptUtil.maskInterruptFlag();
someOtherThread.join(delay);
} catch(InterruptedException e) {
// reachable only if join does not succeed within delay.
// Without the maskInterruptFlag() call, the join() would have returned immediately
// had the current thread been interrupted previously, i.e. before entering the above block
} finally {
interruptUtil.unmaskInterruptFlag();
}