Merge topic 'clang-format-attrs'

d22c2743 clang-format.bash: Use Git attributes to mark files for formatting
6365886c Define a custom Git attribute to mark sources using our C style
0af48083 Drop custom Git whitespace check attribute

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: Ben Boeckel <ben.boeckel@kitware.com>
Merge-request: !18