* x86-64-tdep.c (RET_INT_REGS, RET_SSE_REGS): Remove defines.

* x86-64-tdep.c (RET_INT_REGS, RET_SSE_REGS): Remove defines.
(x86_64_use_struct_convention, x86_64_extract_return_value,
x86_64_store_return_value): Remove.
(amd64_reg_class): New enum.
(amd64_merge_classes, amd64_classify_aggregate, amd64_classify,
amd64_return_value): New functions.
(x86_64_init_abi): Don't set extract_return_value,
store_return_value and use_struct_convention.  Set return_value to
amd64_return_value.
* i387-tdep.h (i387_return_value): New prototype.
* i387-tdep.c (i387_return_value): New function.