MSVC flags shouldn't be needed for XS compilation
Define HAS_BOOL in source, not via compiler flags
Switch to Module::Build->depends_on

According to the Module::Build documentation, 'depends_on' is preferred
over 'dispatch' when calling actions from inside another action.

Calling 'dispatch' also has the side effect of localizing the
Module::Build properties hash. This makes it impossible to call an
action which changes some properties and use the changed properties
afterwards. The next commit relies on this feature.
Remove dependency of Clownfish::CFC::Perl::Build on Charmonizer

Add a new field 'cflags' to the 'clownfish_params' Module::Build
property to pass additional compiler flags.
Set -fvisibility flag via charmonizer
Bake parcel privacy defines into XS

The XS code can now be compiled without any extra compiler flags.