[rfa(arm)/rfc] Eliminate HOST_{FLOAT,DOUBLE,...}_FORMAT

[Andrew Cagney <ac131313@cygnus.com>]

Hello,

The attatched should catch a few eyebrows :-)

The existing GDB tries to be smart about converting host/target floating 
point values - if it thinks that host-float == target-float then it just 
does a move instead of a conversion.

This patch eliminates the short cut.  Instead the conversion is always 
routed through floatformat_{to,from}_doublest().  The most telling 
comment and the reason this will probably catch a few eyebrows can be 
found in i387-tdep.c:

!   /* Avoid call to floatformat_to_doublest if possible to preserve as
!      much information as possible.  */

To me, the comment doesn't make sense.  If sizeof (host long double) == 
size of (target long double) and information is still being lost then I 
think floatformat_* has a bug.

As a side effect it also cleans up the ARM target-float -> 
target->double conversion so that it is more portable (well I think it is).

Comments?  Approval for the ARM part?  I can/should separate the arm 
part out.

	Andrew