Remove all FATAL_IFs from graphicsstats service

As graphicsstats can be subjected to data coming
from the disk and is in system_server we want
to bias towards best-effort instead of strict
no-errors that the rest of HWUI typically uses.

So treat any dump/merge of graphics stats as
best effort, ignoring any errors that occur.

Bug: 65652900
Test: verified 'dumpsys graphicsstats' still works

Change-Id: Ia9b91b745c2a9aedad2f22e3087e1d4bf37a1135