[patch/rfc] Add host's floatformat

[Andrew Cagney]

[picking up a really old thread]

>>Really, I don't see why this is better than a hardwired table
>>> mapping CPU to floating point format.
> 
> 
> Because most FPUs are IEEE, so except for the ones that aren't, it
> will auto-detect the FPU type.  Having a table means that CPUs default
> to "broken", rather than defaulting to "probably works".
> 
> It also means we don't have to keep tweaking the table as people
> change their minds about CPU naming schemes

This assume that the floatformat code works.

Below is a table generated by using floatformat to convert the double 
1.0 into the corresponding architecture format.  Notice the arm_ext_big 
/ arm_littlebyte_bigword and double_big / double_littlebyte_bigword pairs:

3f800000                         floatformat_ieee_single_big
0000803f                         floatformat_ieee_single_little
3ff0000000000000                 floatformat_ieee_double_big
000000000000f03f                 floatformat_ieee_double_little
3ff0000000000000                 floatformat_ieee_double_littlebyte_bigword
0000000000000080ff3f             floatformat_i387_ext
3fff8000000000000000             floatformat_m88110_ext
3fff00008000000000000000         floatformat_m68881_ext
0000000000000080ff3f0000         floatformat_i960_ext
00003fff8000000000000000         floatformat_arm_ext_big
00003fff8000000000000000         floatformat_arm_ext_littlebyte_bigword
3ff00000000000000000000000000000 floatformat_m88110_ext_harris
3fffe000000000000000000000000000 floatformat_ia64_spill_big
00000000000000000000000000e0ff3f floatformat_ia64_spill_little
3fff0000000000000000000000000000 floatformat_ia64_quad_big
0000000000000000000000000000ff3f floatformat_ia64_quad_little

I'm withdrawing my patch.  I'll instead fix this as MarkK suggested - 
local to GDB.

Andrew