CMakeLists: Generate the cmCommands.cxx file.

Define the list of commands in the CMakeLists.txt file. List the
sources in the CMakeLib target, but mark them as HEADER_FILE_ONLY.
This has the effect that IDEs will show the files, though they
will not be built again.

Add a cmCommandsForBootstrap.cxx file for bootstrapping purposes.

Rename the cmExportLibraryDependencies file to match the common
pattern.
Merge topic 'generate-cmCommands-file' into next

23d3d38a CMakeLists: Generate the cmCommands.cxx file.
Remove the Example from the source.

It is not showing modern practice, and is obsolete as documentation
after the rst documentation system and new content.
Merge topic 'remove-Example' into next

2e615d4b Remove the Example from the source.