* upstream-KWSys:
KWSys 2017-03-24 (7e9f7b7b)
Resolve conflicts in `.gitattributes` by integrating changes from both
sides. Keep the `our-c-style` attribute that KWSys uses, but drop their
definition of it in favor of ours (Git only allows custom attributes in
the top level anyway). Then add our own attribute line to unset the
`format.clang-format` attribute for KWSys sources since we do not want
to format third-party code ourselves.
KWSys upstream added an attribute to export .gitattributes so that
importing snapshots into the sources of other projects would bring along
the attributes. However, we don't want to export them from CMake.
Drop .gitattributes entries not relevant to CMake.
