Add some functions for hugepage test.

Add to virttest/staging/utils_memory.py
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
get_transparent_hugepage() : get the transparent_hugepages() is enable or disable
set_transparent_hugepage() : set the transparent_hugepages() enable or disable

Add to virttest/libvirt_xml/vm_xml.py
set_hugepage_tag(vm_name) : add a hugepage tag to a vm

shared/scripts/hugepage_mem_test.c prepare to hugepages memory test.

Signed-off-by: Weiqing Wang <wangwq.fnst@cn.fujitsu.com>