add Text.ParserCombinators.ReadP, Text.ParserCombinators.ReadPrec and
Text.Read.Lex to Hugs. (But they're not used by Read, because that
would make the Prelude non-H98).
Data.PackedString uses Data.Array.Unboxed
Debug.QuickCheck.Batch needs pre-emptive concurrency
System.Posix.Signals
-Text.ParserCombinators.ReadP ReadS clashes with Prelude
-Text.ParserCombinators.ReadPrec uses ReadP
-Text.Read.Lex uses ReadP