rs6000.c 64-bit hosting

[David Edelsohn]

>>>>> Geoff Keating writes:

>> * rs6000.c (rs6000_{init,free}machine_status): Declare prototypes.
>> (rs6000_emit_move): Only emit TOC constant for hard constants.
>> Merge special_constant_p test into the test just after.
>> 
Geoff> [patch snipped.]

Geoff> That looks reasonable.  Of course, it'd need lots of testing.

	The problem with 64-bit constants is the code to generate a
constant needs to be cleaned up into a C function instead of the various
splitters. 

David