add sample script scripts/syscalls/execve.kp

Example:

	# ./ktap scripts/syscalls/execve.kp

	[do_execve entry]: (bash) name=/usr/bin/ls
	[do_execve entry]: (bash) name=/usr/bin/top
	[do_execve entry]: (bash) name=/usr/bin/ls
	...

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