Add 3 functions to utils_memory for getting some usage info of hugepages.

get_num_anon_huge_pages(pid) : get the anonhugepages' usage amount of a progress
get_num_huge_pages_free() : get the number of free hugepages
get_num_huge_pages_rsvd() : get the number of rsvd hugepages
When I wrote this code , I just followed the way used to take . 
I will make some change. Thank you!