cmd/cc: emit size of locals.  Will be used for stack copying.
cmd/cc: emit size of locals.  Will be used for stack copying.

R=cshapiro, dvyukov, khr, rsc
CC=golang-dev
https://codereview.appspot.com/10005044

gnanderson/go,gnanderson/go,gnanderson/go,apparentlymart/golang,apparentlymart/golang,tv42/old-go,pombredanne/go-deleteme,tv42/old-go,pombredanne/go-deleteme,pombredanne/go-deleteme,tv42/old-go,apparentlymart/golang,pombredanne/go-deleteme,apparentlymart/golang,gnanderson/go,apparentlymart/golang,gnanderson/go,tv42/old-go,pombredanne/go-deleteme,pombredanne/go-deleteme,pombredanne/go-deleteme,tv42/old-go,apparentlymart/golang,apparentlymart/golang,gnanderson/go,gnanderson/go,tv42/old-go,tv42/old-go