[release-branch.go1] runtime: fix c compiler warning

««« backport e388ce51be75
runtime: fix c compiler warning

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6185047

»»»

src/pkg/runtime/vlrt_arm.c

@@ -197,12 +197,14 @@ void
 runtime·int64tofloat64(Vlong y, double d)
 {
 	d = _v2d(y);
+	USED(&d); // FLUSH
 }
 
 void
 runtime·uint64tofloat64(Vlong y, double d)
 {
 	d = _ul2d(y.hi)*4294967296. + _ul2d(y.lo);
+	USED(&d); // FLUSH
 }
 
 static void