test: disable the live test on riscv64

This test expects that open-coded defers are enabled, which is not currently
the case on riscv64.

Updates issue #27532 and #36786.

Change-Id: I94bb558c5b0734b4cfe5ae12873be81026009bcf
Reviewed-on: https://go-review.googlesource.com/c/go/+/216777
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

test/live.go

@@ -1,8 +1,13 @@
 // errorcheckwithauto -0 -l -live -wb=0 -d=ssa/insert_resched_checks/off
-// +build !ppc64,!ppc64le
+// +build !ppc64,!ppc64le,!riscv64
+
 // ppc64 needs a better tighten pass to make f18 pass
 // rescheduling checks need to be turned off because there are some live variables across the inserted check call
 
+// TODO(jsing): these tests assume that open-coded defers are enabled,
+// which is not currently the case on riscv64. Re-enable this test once
+// open-coded defers are available - golang.org/issues/36786.
+
 // Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.