[patch/rfc] Delete floatformat_arm_ext

[DJ Delorie]

> The attached deletes floatformat_arm_ext from include/floatformat.h and 
> libiberty/floatformat.c.  As far as I know nothing uses it.  GDB stopped 
> using it some time ago.

In general, I'm opposed to changes that reduce backward compatibility.
*How* long ago did someone actually use it?  What's the chance of that
version still being in use by someone?  Are there any bad side-effects
if we just leave it in for historical reasons?