PR16716 partial fix: Better types in 'syscall.{listen,setsockopt}'.

PR16716 partial fix: Better types in 'syscall.{listen,setsockopt}'.

* tapset/linux/syscalls.stp (syscall.listen): Fix types.
* tapset/linux/syscalls2.stp (syscall.setsockopt): Ditto.
* tapset/linux/nd_syscalls2.stp (nd_syscall.setsockopt): Fix types.
* testsuite/systemtap.syscall/getsockopt.c: Fixed typo.
* testsuite/systemtap.syscall/listen.c: Added test.
* testsuite/systemtap.syscall/setsockopt.c: New test case.