Real.maxFinite and friends

[Matthew Fluet]

Well, any new datatypes and major changes to Real will have to wait until
after SSA and the new backend changes are in.  I'll go ahead and convert
the Real constants to _prim's, since that won't be too hard.  Actually, it
will be hard.  Nullary _prim's are compile time constants, so they will be
read in using the lookup-constants program.  And you can't write down
maxFinite (and friends) as a string that is read in to the right set of
bits; I tried.  Hmmm...  what we should really do is have lookup-constants
print floats as two words of hex and then read those into PackReal and
convert.  Blech; that still doesn't solve the problem, because real
constants are placed in the .c stub file as strings.  So, have two types
of global reals -- ones as string and ones as words of hex?  This is
getting more complicated than I thought.