Add .git-blame-ignore-revs
Add .git-blame-ignore-revs

Git has an ability to ignore revisions when using `git blame`, which can
be configured locally via

git config blame.ignoreRevsFile .git-blame-ignore-revs

The particular name seems to be a common convention, including being
automatically picked up by GitHub.

CL ignored in the list: https://r.android.com/2116064

Change-Id: Ia34749d867b5f77dd756dfc341b24e1c4d095ea0

google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto