Add method for reading VmRSS from status am: 0f208eb2aa am: 8f09e4fb78 am: 7681c6ac87 am: a36c697040

Original change: https://android-review.googlesource.com/c/platform/system/memory/libmeminfo/+/2741414

Change-Id: Iafaf7dc4fc26be4c1c25f39117851a85c186d2b0
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>