Remove legacy +build: constraint (#19582)

Go 1.17 and later use modern `//go:build` constraints, the old `// +build:` constraints should be removed.

Author: wxiaoguang

build.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build vendor
-// +build vendor
 
 package main
 

build/code-batch-process.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build ignore
-// +build ignore
 
 package main
 

build/generate-bindata.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build ignore
-// +build ignore
 
 package main
 

build/generate-emoji.go

@@ -4,7 +4,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build ignore
-// +build ignore
 
 package main
 

build/generate-gitignores.go

@@ -1,5 +1,4 @@
 //go:build ignore
-// +build ignore
 
 package main
 

build/generate-licenses.go

@@ -1,5 +1,4 @@
 //go:build ignore
-// +build ignore
 
 package main
 

build/gitea-format-imports.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build ignore
-// +build ignore
 
 package main
 

build/gocovmerge.go

@@ -7,7 +7,6 @@
 // merges them into one profile
 
 //go:build ignore
-// +build ignore
 
 package main
 

cmd/embedded.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build bindata
-// +build bindata
 
 package cmd
 

cmd/embedded_stub.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !bindata
-// +build !bindata
 
 package cmd