libmeminfo: Add THP field to procmem output am: f6ad0be442 am: 98549ee03c am: 75e0c797cb

Original change: https://android-review.googlesource.com/c/platform/system/memory/libmeminfo/+/1677671

Change-Id: I4fe506255bca14eb9884df4df942424fd1d11207