add sample script syscalls/syslatl.kp and syscalls/syslist.kp

scripts/syscalls/syslatl.kp: syscall latency linear aggregation
scripts/syscalls/syslist.kp: syscall latency as a list with counts

Both of these two scripts was created by Brendan Gregg.

Some basic ktap examples wroten by Brendan Gregg:
	http://www.brendangregg.com/ktap.html

Signed-off-by: Jovi Zhangwei <jovi.zhangwei@gmail.com>