test: migrate remaining files to go:build syntax

Most of the test cases in the test directory use the new go:build syntax
already. Convert the rest. In general, try to place the build constraint
line below the test directive comment in more places.

For #41184.
For #60268.

Change-Id: I11c41a0642a8a26dc2eda1406da908645bbc005b
Cq-Include-Trybots: luci.golang.try:gotip-linux-386-longtest,gotip-linux-amd64-longtest,gotip-windows-amd64-longtest
Reviewed-on: https://go-review.googlesource.com/c/go/+/536236


Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

src/cmd/compile/internal/types2/stdlib_test.go

@@ -191,7 +191,7 @@ func firstComment(filename string) (first string) {
 		}
 		text = strings.TrimSpace(text[2:])
 
-		if strings.HasPrefix(text, "+build ") {
+		if strings.HasPrefix(text, "go:build ") {
 			panic("skip")
 		}
 		if first == "" {

src/go/types/stdlib_test.go

@@ -192,7 +192,7 @@ func firstComment(filename string) string {
 				lit = lit[:len(lit)-2]
 			}
 			contents := strings.TrimSpace(lit[2:])
-			if strings.HasPrefix(contents, "+build ") {
+			if strings.HasPrefix(contents, "go:build ") {
 				return "skip"
 			}
 			if first == "" {

test/abi/bad_internal_offsets.go

 // compile
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/double_nested_addressed_struct.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/double_nested_struct.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/f_ret_z_not.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/fibish.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/fibish_closure.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/leaf.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/leaf2.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/many_int_input.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/many_intstar_input.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/more_intstar_input.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/named_results.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/named_return_stuff.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/reg_not_ssa.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2023 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/return_stuff.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/s_sif_sif.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/spills3.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/abi/spills4.go

 // run
 
 //go:build !wasm
-// +build !wasm
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style