Make ghc compilable with itself after the implementation of handle
IO changed, by changing an ugly mess of #ifdefs and low-level
ghc-internals-specific kludges into a yet uglier mess with more
#ifdefs and kludges.

Wouldn't Haskell 98 implementation of a lexer be fast enough? :-)

This won't compile with older versions of ghc-5.01. You may temporarily
change 501 to 502 in #ifdefs here, or use an older ghc.

The compiler still doesn't work at all when compiled with itself:
it writes complete nonsense into .hc files.

A remaining error: ghc/lib/std doesn't link PrelHandle_hsc.o into
libHSstd.a. Function read_wrap is inline but for some reason it's
needed for linking some programs (e.g. ghc itself).