Add implicit ctor even for =Any field initializer

For consistency with other field initializers, and also to cause to =Any
initializer to have some effect when the UDT wouldn't otherwise have a
constructor, because field initializers are currently only used inside
constructors to replace the default clear. Without the constructor they'd
be ignored.

http://www.freebasic.net/forum/viewtopic.php?p=191119#p191119