-Werror,-Wconstant-conversion

"implicit conversion from 'long' to 'sal_uInt16' (aka 'unsigned short') changes
value from 9223372036854775807 to 65535," and at least the call to getHandle for
the long nHand argument of SwFltControlStack::SetAttr in
SwWW8ImplReader::Read_AtnBook makes it look like it better return long?

Change-Id: I594ac3ee60a72c0eb2e13f802371ff1e8ade7676