Mostly from suggestions, but there's a couple of other minor
fixes and additions:
Cmake not decides with SDK to use on Windows
All Audacity cmake options are not prefixed with "audacity_", but this
is configurable in audacity/CMakeLists.txt
Several other options have been marked advanced so they don't clutter
the CMake GUI
On Windows, multiple processors will now be used reducing build time
considerably
Quieted a couple of package messages that the user doesn't need to see
No longer tried to create aliases on Windows
No longer used precompiled headers if ccache is available
On Windows, only copies the needed wxWidgets and VC runtime libraries
to the bin directory
e79274a403