5c: make alignment rules match 5g, just like 6c matches 6g

5c: make alignment rules match 5g, just like 6c matches 6g

I should have done this a year ago in:

        changeset:   5137:686b18098944
        user:        Russ Cox <rsc@golang.org>
        date:        Thu Mar 25 14:05:54 2010 -0700
        files:       src/cmd/8c/swt.c
        description:
        make alignment rules match 8g, just like 6c matches 6g.

        R=ken2
        CC=golang-dev
        https://golang.org/cl/760042

R=ken2
CC=golang-dev
https://golang.org/cl/4437054