gdb: info breakpoints显示所有断点

效果如下，

(gdb) info br
Num     Type           Disp Enb Address            What
1       breakpoint     keep y   <PENDING>          vtysh_init_vty
4       breakpoint     keep y   0x00007ffff42bda0f in main at isis_main.c:348
	breakpoint already hit 1 time
6       breakpoint     keep y   <MULTIPLE>         
	breakpoint already hit 3 times
6.1                         y     0x00007ffff4303294 in zlog_set_level at log.c:664
6.2                         y     0x00007ffff48e0b10 in zlog_set_level at log.c:664
7       breakpoint     keep y   <MULTIPLE>         
7.1                         y     0x00007ffff4301418 in vzlog at log.c:151
7.2                         y     0x00007ffff48dec94 in vzlog at log.c:151