runtime: fix solaris build

CL 144830043 changed LibCall for Windows.
I didn't realize Solaris used it too.

TBR=iant
CC=golang-codereviews
https://codereview.appspot.com/142100043
runtime: fix solaris build, part 2

This file was already assigned to another CL
so it didn't make it into the build fix CL. Sigh.

TBR=iant
CC=golang-codereviews
https://codereview.appspot.com/144850043
syscall: add GO_ARGS to Go-called assembly

Fixes sporadic linux/386 build failure (untyped args)
and probably some others we haven't observed yet.

Fixes issue 8727.

TBR=iant
R=golang-codereviews
CC=bradfitz, golang-codereviews, iant, khr, r
https://codereview.appspot.com/143930043