liblink: fix extern register accesses on Plan 9 (386)
liblink: fix extern register accesses on Plan 9 (386)

R=golang-dev, 0intro, rsc
CC=golang-dev
https://codereview.appspot.com/39680044

Committer: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>

apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang