.clang-format: update to 3.8.1

based on --style=Google with the following differences:
3a4
> # Generated with clang-format 3.8.1
13c14
< AllowShortCaseLabelsOnASingleLine: false
---
> AllowShortCaseLabelsOnASingleLine: true
41c42
< ConstructorInitializerAllOnOneLineOrOnePerLine: true
---
> ConstructorInitializerAllOnOneLineOrOnePerLine: false
44,45c45,46
< Cpp11BracedListStyle: true
< DerivePointerAlignment: true
---
> Cpp11BracedListStyle: false
> DerivePointerAlignment: false
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< PointerAlignment: Left
---
> PointerAlignment: Right
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< SortIncludes:    true
---
> SortIncludes:    false

SortIncludes will like be enabled in a future commit

Change-Id: I34cb20b99d2d988681e0cd0e74d03b3668ae0031