Hi,

The attached patch implements the calling convention for decimal
floating point in x86 32-bits and x86_64 (arguments and return value).
Now all DFP tests pass in these architectures.

For x86 it was very easy. The only case which needs special attention is
a function returning a _Decimal128 value, which uses struct return
convention.

For x86_64, I just had to update the classification function with the
proper class for the DFP types, as specified by the AMD64 ABI Draft
version 0.99.

This patch introduces no regression (tested in Linux/i686 and
Linux/x86_64). Ok to commit?
-- 
[]'s
Thiago Jung Bauermann
Software Engineer
IBM Linux Technology Center