Replace stringstream with std::cout and std::cerr am: 97abf1512c am: 0194ee19b1 am: 5ee046ce3a

Original change: https://android-review.googlesource.com/c/platform/system/memory/libmeminfo/+/2249886

Change-Id: I8a95739a46d60168ad9b17fe27867d7b3a5b3052
Signed-off-by: Automerger Merge Worker <[email protected]>