please add DFP to gcc-4.3/changes.html

[Benjamin Kosnik]

HJ asked this in June 2007:
http://gcc.gnu.org/ml/gcc/2007-06/msg00144.html

It seems as if delaying the announcement was what was desired then. Is
this still the case?

I was just as surprised as HJ was to not find this documented anywhere.
I'd rather have it documented, and marked experimental if it be.

The situation right now is very confusing.

-benjamin