regclass.c: scan_one_insn special casing

[Richard Kenner]

    > Sure, but it's better to do something in *machine-independent* code if
    > you can.

    Then why bother having define_split?

For those very few cases that are machine-specific.

    There's just something wrong with special casing all over the compiler
    just for a small case that could/should be handled somewhere else.

But I feel that this case should be handled right where ti is and that's
the best place to put it.

How is it better to put this in a define_split in each port?