misc/cgo/test: re-enable darwin cgo tests in race mode

Go 1.14 will drop support for macOS 10.10, see #23011

This reverts CL 125304

Updates #26475
Updates #26513

Change-Id: Ia13eef30f22d67103f7ae45424124fbb116e1261
Reviewed-on: https://go-review.googlesource.com/c/go/+/214057
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

misc/cgo/test/issue21897.go

@@ -2,16 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// We skip this test in race mode because, for unknown reasons,
-// linking against CoreFoundation on macOS 10.10 causes mmap to ignore
-// the hint address, which makes the Go allocator incompatible with
-// TSAN. See golang.org/issue/26475.
-//
-// TODO(austin): Once support for macOS 10.10 is dropped, remove the
-// race constraint (and the one in issue21897b.go). See
-// golang.org/issue/26513.
-
-// +build darwin,cgo,!internal,!race
+// +build darwin,cgo,!internal
 
 package cgotest
 

misc/cgo/test/issue21897b.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !darwin !cgo internal race
+// +build !darwin !cgo internal
 
 package cgotest
 

misc/cgo/test/testdata/issue24161_darwin_test.go

@@ -2,14 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// See issue21897.go and golang.org/issue/26475 for why this is
-// skipped in race mode.
-//
-// TODO(austin): Once support for macOS 10.10 is dropped, remove the
-// race constraint. See golang.org/issue/26513.
-
-// +build !race
-
 package cgotest
 
 import (