ConfigFlags { configConfigurationsFlags } field should contain flags which are defined in .cabal file, but aren't specified in command line with -flags=...

(Imported from [Trac #778](http://hackage.haskell.org/trac/hackage/ticket/778), reported by @nartamonov on 2010-12-17)

I have custom Flag declaration in .cabal file:

Flag debug

Description: Build with debug support
Default: True

and some conditionals (if flag(debug) ...) which depend on this flag. In custom Setup.hs I use data structure Distribution.Simple.Setup.`ConfigFlags?` and its field configConfigurationsFlags to get value of 'debug' flag. But it seems that field contains flag entry only when I explicitly mention flag during configuration phase in command line with '-fdebug' or '--flags=debug'.

I think it is wrong because even if I don't mention flag in command line he will be initialized to True and conditionals (in *.cabal) which depend on it will be evaluated according to this default value. It would be awesome if I could access flag with its implicitly assigned value via `ConfigFlags?` { configConfigurationsFlags }.

My custom Setup.hs machinery heavily depends on values of such flags, and it is inconvenient to explicitly define all of them via command line during configuration phase.

Thanks.