support list events

Usage: ktap -le [glob]

[root@localhost ktap]# ./ktap -le
irq_vectors:thermal_apic_exit
irq_vectors:thermal_apic_entry
irq_vectors:threshold_apic_exit
irq_vectors:threshold_apic_entry
...

[root@localhost ktap]# ./ktap -le | wc -l
911

[root@localhost ktap]# ./ktap -le syscalls:sys_enter_*
syscalls:sys_enter_mmap
syscalls:sys_enter_unshare
syscalls:sys_enter_set_tid_address
syscalls:sys_enter_personality
...

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