Detect when a module is compiled but not listed in the cabal file

[snoyberg]

Would have caught this bug @chrisdone just introduced ;)

/home/vagrant/haskell/stackage-common/dist/build/libHSstack-0.0.0.a(Config.o):(.text+0x1cb7f): undefined reference to `stackzm0zi0zi0_StackziTypesziDocker_zdwzdcshowsPrec_info'
/home/vagrant/haskell/stackage-common/dist/build/libHSstack-0.0.0.a(Config.o):(.data+0x3250): undefined reference to `stackzm0zi0zi0_StackziTypesziDocker_zdfFromJSONZLzmzgZRzuzdcparseJSON_closure'
/home/vagrant/haskell/stackage-common/dist/build/libHSstack-0.0.0.a(Config.o):(.data+0x3490): undefined reference to `stackzm0zi0zi0_StackziTypesziDocker_zdfFromJSONZLzmzgZRzuzdcparseJSON_closure'
/home/vagrant/haskell/stackage-common/dist/build/libHSstack-0.0.0.a(Config.o):(.data+0x3658): undefined reference to `stackzm0zi0zi0_StackziTypesziDocker_zdwzdcshowsPrec_closure'
/home/vagrant/haskell/stackage-common/dist/build/libHSstack-0.0.0.a(Config.o):(.text+0x2797): undefined reference to `stackzm0zi0zi0_StackziTypesziDocker_zdwzdcshowsPrec_info'
/home/vagrant/haskell/stackage-common/dist/build/libHSstack-0.0.0.a(Config.o):(.data+0x9c0): undefined reference to `stackzm0zi0zi0_StackziTypesziDocker_zdwzdcshowsPrec_closure'

FYI: I'm fixing that problem in the codebase right now

[snoyberg]

@dysinger Please have a look at this one. I'm not sure of the best way to determine which modules were built by runghc Setup.hs build.

[snoyberg]

Just spoke with Dan about this, it will fit in with other work he's doing.