Convert libsmapinfo stringstreams to ostreams am: 44d6fd606e am: ec71dc2330 am: 622e072b6f am: 4ddbfba0bf am: 0bd194f8d0

Original change: https://android-review.googlesource.com/c/platform/system/memory/libmeminfo/+/2189640

Change-Id: I37c17f6e67cebf8a48345782df76ea2c8c1b5180
Signed-off-by: Automerger Merge Worker <[email protected]>