all: use "unix" build tag where appropriate

Convert a few occurrences that were submitted after CL 389935.

For #20322
For #51572

Change-Id: I0047361916c402f8e37f515e6b09d451bd499e6e
Reviewed-on: https://go-review.googlesource.com/c/go/+/437235
TryBot-Result: Gopher Robot <[email protected]>
Run-TryBot: Tobias Klauser <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>
Auto-Submit: Tobias Klauser <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: tklauser

Diff for: src/cmd/internal/osinfo/os_unix.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.
 
-//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
+//go:build unix
 
 package osinfo
 

Diff for: src/os/rlimit.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.
 
-//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
+//go:build unix
 
 package os
 

Diff for: src/runtime/pprof/pprof_rusage.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.
 
-//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
+//go:build unix
 
 package pprof
 

Diff for: src/runtime/pprof/rusage_test.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.
 
-//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
+//go:build unix
 
 package pprof
 

Diff for: src/syscall/mmap_unix_test.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.
 
-//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
+//go:build unix
 
 package syscall_test