runtime: fix arm build

R=adg, dfc, r
CC=golang-dev
https://golang.org/cl/4296042
diff --git a/src/pkg/runtime/linux/arm/sys.s b/src/pkg/runtime/linux/arm/sys.s
index 2b01f0c..b9767a0 100644
--- a/src/pkg/runtime/linux/arm/sys.s
+++ b/src/pkg/runtime/linux/arm/sys.s
@@ -73,10 +73,10 @@
 	SWI	$0
 	RET
 
-TEXT runtime·getitimer(SB),7,$0
+TEXT runtime·setitimer(SB),7,$0
 	MOVW	0(FP), R0
 	MOVW	4(FP), R1
-	MOWW	8(FP), R2
+	MOVW	8(FP), R2
 	MOVW	$SYS_setitimer, R7
 	SWI	$0
 	RET