Add a dependency of program modules on GHC.TopHandler

If you were unlucky, the build could fail, e.g.:

utils\mkUserGuidePart\Main.hs:1:1:
    Failed to load interface for `GHC.TopHandler'
    There are files missing in the `base' package,
    try running 'ghc-pkg check'.
    Use -v to see a list of the files searched for.
utils/mkUserGuidePart/ghc.mk:18: recipe for target `utils/mkUserGuidePart/dist/build/Main.o' failed