add uid() built-in function

Similar usage as pid() and tid().

Signed-off-by: Jovi Zhangwei <jovi.zhangwei@gmail.com>
add -q (quiet) command option

Now if ktap wait user press Control+C to stop tracing,
then ktap will print a default message:
	Tracing... Ctrl-C to end.

If user don't want this message, then user can give -q
option, this quiet option is useful for some cases like
need to parse ktap execution output(flame graph).

Signed-off-by: Jovi Zhangwei <jovi.zhangwei@gmail.com>
add symbol annotation into kprobe argname

Before:
                          value ------------- Distribution ------------- count
                             kp0 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@          71
                             kp1 |@@@@@@@@@                              24

After:

                          value ------------- Distribution ------------- count
                    kp0_vfs_read |@@@@@@@@@@@@@@@@@@@@@@                 4
                   kp1_vfs_write |@@@@@@@@@@@@@@@@                       3

Users may like those keys to be "vfs_read", "vfs_write", and not "kp0", "kp1".

This issue was reported by Brendan Gregg.

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