Fix <android-base/*.h> header guards.

I've been meaning to do this for a while, and it came up on the bug below
that there have been conflicts with similar-named files in <base/*.h>,
so let's rule out one possible explanation.

Bug: http://b/27804373
Change-Id: I69e5d52b6260c573c308513420aee0e281426bd4
13 files changed