Fix parsing of OPTIONS*/LANGUAGE pragmas in haddock mode
When getting options from basicTypes/RdrName.lhs, we were seeing text like "-- |\n-- ...\n" in the buffer, and lexer then recognises "-- |\n-- ..." as a complete ITdocCommentNext token, with the end of the buffer not reached. Next time round, when we get more input into the buffer, it started "\n-- * 'Var.Var': see", so the lexer gave us an ITdocSection token. However, getOptions' only knew about ITdocCommentNext, and so it stopped at that point, and didn't see the pragmas further down the file. This caused the build to fail due to -fwarn-tabs not being turned off. But actually, we don't really want the haddock docs at this point, so now we just unset Opt_Haddock in getOptionsFromFile.