Fix golangci-lint warnings (#17598 et al) (#17668)

Backport #17598 
Backport #17606 
Backport #17608 
Backport #17609

- Since https://gitea.com/gitea/test-env/pulls/10 the golangci-lint has been upgraded and is erroring about new warnings in the code, this PR fixes those warnings.

Author: Gusted

.golangci.yml

@@ -9,7 +9,6 @@ linters:
     - unused
     - structcheck
     - varcheck
-    - golint
     - dupl
     #- gocyclo # The cyclomatic complexety of a lot of functions is too high, we should refactor those another time.
     - gofmt

build.go

@@ -2,7 +2,8 @@
 // Use of this source code is governed by a MIT-style
 // license that can be found in the LICENSE file.
 
-//+build vendor
+//go:build vendor
+// +build vendor
 
 package main
 

build/generate-bindata.go

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a MIT-style
 // license that can be found in the LICENSE file.
 
+//go:build ignore
 // +build ignore
 
 package main

build/generate-emoji.go

@@ -3,6 +3,7 @@
 // Use of this source code is governed by a MIT-style
 // license that can be found in the LICENSE file.
 
+//go:build ignore
 // +build ignore
 
 package main

build/generate-gitignores.go

@@ -1,3 +1,4 @@
+//go:build ignore
 // +build ignore
 
 package main

build/generate-licenses.go

@@ -1,3 +1,4 @@
+//go:build ignore
 // +build ignore
 
 package main

build/gocovmerge.go

@@ -6,6 +6,7 @@
 // gocovmerge takes the results from multiple `go test -coverprofile` runs and
 // merges them into one profile
 
+//go:build ignore
 // +build ignore
 
 package main

cmd/docs.go

@@ -43,7 +43,11 @@ func runDocs(ctx *cli.Context) error {
 		// Clean up markdown. The following bug was fixed in v2, but is present in v1.
 		// It affects markdown output (even though the issue is referring to man pages)
 		// https://github.com/urfave/cli/issues/1040
-		docs = docs[strings.Index(docs, "#"):]
+		firstHashtagIndex := strings.Index(docs, "#")
+
+		if firstHashtagIndex > 0 {
+			docs = docs[firstHashtagIndex:]
+		}
 	}
 
 	out := os.Stdout

cmd/embedded.go

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a MIT-style
 // license that can be found in the LICENSE file.
 
+//go:build bindata
 // +build bindata
 
 package cmd

cmd/embedded_stub.go

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a MIT-style
 // license that can be found in the LICENSE file.
 
+//go:build !bindata
 // +build !bindata
 
 package cmd