Run the `Utilities/Scripts/clang-format.bash` script to update
all our C++ code to a new style defined by `.clang-format`.
Use `clang-format` version 3.8.
* If you reached this commit for a line in `git blame`, re-run the blame
operation starting at the parent of this commit to see older history
for the content.
* See the parent commit for instructions to rebase a change across this
style transition commit.
Add a test case that enables CXX in the top level and C in a subdirectory.
Create an executable in the top level that uses C objects compiled in the
subdirectory. Strictly speaking this is not defined behavior for all
language combinations, but happens to work in this case. Test this
behavior since projects might try to use it.