devel/cdecl: upgrade to 6.6.
Defaulted & deleted support
Defaulted & deleted special member functions are now supported.
Both a command-line --explain/-e and explain-by-default set option have been added that assume a command that doesn't start with any command means explain.
Set option abbreviations
Unambiguous set option name abbreviations may now be used.
Virtual constexpr declarations are now only correctly allowed in C++20.