need to determine (kernel doco, yea right), and test a system call being
interrupted - is there always sysenter and sysexit; or sysenter and syscall?
New test frysk.proc.TestSyscallInterrupt added which tests attaching to a
process currently in a blocked read and properly tracing syscall enter and exit.
The test signals the process so that the read is interrupted and is performed a
2nd time allowing the read to restart.
Test runs successfully and in both cases we see sysenter / sysexit pairs
properly determined by TaskState transitions.