stubdir D adds an implicit -I D, so that gcc can find the _stub.h file
  -- \#included from the .hc file when compiling via C (i.e. unregisterised
  -- builds).
setDumpDir    f d = d{ dumpDir    = Just f}
set
setDumpDir    f d = d{ dumpDir    = Just f}
setDumpDir    f d = d{ dumpDir    = Just f}