Suppress some cases in `Source/cmGeneratorExpressionNode.cxx` and
`Source/cmUVHandlePtr.h` where a few older compilers require a
user-defined default constructor (with `{}`).
Run the `clang-format.bash` script to update all our C and C++ code to a
new style defined by `.clang-format`. Use `clang-format` version 6.0.
* 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.
The `uv_*_t` handle types are closed by `uv_close`, but the semantics
are tricky. Calling `uv_close` may not close immediately. Instead it
hands ownership to the uv loop to which the handle is currently
attached. When the loop decides to close it, a callback is used to
allow the `uv_close` caller to free resources.
Provide an abstraction layer as `cm::uv_*_ptr` types corresponding to
the `uv_*_t` handle types. Each pointer is either empty (`nullptr`)
or has an initialized handle attached to a loop. Use move semantics
to ensure a single owner of the handle so that clients can predict
when the handle is destroyed.
