staging: add ktap

This patch introduces ktap to staging tree.

KTAP is a new scripting dynamic tracing tool for Linux,
it uses a scripting language and lets users trace the
Linux kernel dynamically. KTAP is designed to give
operational insights with interoperability that allow
users to tune, troubleshoot and extend kernel and application.
It's similar with Linux Systemtap and Solaris Dtrace.

KTAP have different design principles from Linux mainstream
dynamic tracing language in that it's based on bytecode,
so it doesn't depend upon GCC, doesn't require compiling
kernel module for each script, safe to use in production
environment, fulfilling the embedded ecosystem's tracing needs.

See doc/ for more information.

The merit of putting this software in staging tree is
to make it more possible to get feedback from users
and thus polish the code.

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