(i386_extract_return_value): Return directly after issuing the
warning and filling *VALBUF with zeroes if we cannot get at the
floating-point registers.
(i386_store_return_value): New function.
* config/i386/tm-i386.h (STORE_RETURN_VALUE): Simply call
i386_store_return_value.
Add prototype for i386_store_return_value.