* i386-tdep.c (i386_extract_return_value): Use

* i386-tdep.c (i386_extract_return_value): Use
convert_typed_floating to extract floating-point value from
register buffer.
(i386_store_return_value): Use convert_typed_floating to store
floating-point return balue in register buffer
(i386_register_virtual_type): Change type of floating-point
registers to builtin_type_i387_ext.
(i386_register_convert_to_virtual): Use convert_typed_floating to
do the conversion.
(i386_register_convert_to_raw): Likewise.