fix memleaks in luv_cpu_info
fix memleaks in luv_cpu_info

`uv_cpu_info` Gets information about the CPUs on the system.
The cpu_infos array will have count elements and needs to be freed with uv_free_cpu_info().
`uv_free_cpu_info` should be called when get cpu info fail.

zhaozg/luv,zhaozg/luv,luvit/luv,luvit/luv