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 previous implementation assumed that only one byte would be given
in the `from` buffer by the caller at a time. This may be true for
MSVC but is not for the GNU library on Windows. Re-implement these
methods to handle more than one byte per call.
Also simplify the state management by keeping all state between calls
directly in the `mbstate_t` argument instead of using it to index our
own heap-allocated state.
Fixes: #16893
Add a `codecvt` class that can be used as facet for locale so that it's
possible to convert from internal UTF-8 encoding to other encodings such
as Windows ANSI codepage.
