[release-branch.go1.16] runtime/race: use race build tag on syso_test.go

All other test files in the runtime/race package have race build
tag, except syso_test.go. The test is only relevant if the race
detector is supported. So apply the build tag.

Updates #46931.
Fixes #50194.

Change-Id: Icdb94214d3821b4ccf61133412ef39b4d7cc7691
Reviewed-on: https://go-review.googlesource.com/c/go/+/331050
Trust: Cherry Mui <[email protected]>
Reviewed-by: Elias Naur <[email protected]>
Run-TryBot: Cherry Mui <[email protected]>
TryBot-Result: Go Bot <[email protected]>
(cherry picked from commit ed01cea)
Reviewed-on: https://go-review.googlesource.com/c/go/+/372218
Reviewed-by: Dmitri Shuralyov <[email protected]>
Run-TryBot: Dmitri Shuralyov <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: cherrymui

src/runtime/race/syso_test.go

@@ -2,13 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !android,!js,!ppc64le
-
-// Note: we don't run on Android or ppc64 because if there is any non-race test
-// file in this package, the OS tries to link the .syso file into the
-// test (even when we're not in race mode), which fails. I'm not sure
-// why, but easiest to just punt - as long as a single builder runs
-// this test, we're good.
+//go:build race
+// +build race
 
 package race