build: remove build constraint syntax for go 1.16 and older

bin/check-merged.go

@@ -1,5 +1,4 @@
 //go:build ignore
-// +build ignore
 
 // Attempt to work out if branches have already been merged
 package main

bin/cross-compile.go

@@ -1,5 +1,4 @@
 //go:build ignore
-// +build ignore
 
 // Cross compile rclone - in go because I hate bash ;-)
 

bin/get-github-release.go

@@ -1,5 +1,4 @@
 //go:build ignore
-// +build ignore
 
 // Get the latest release from a github project
 //

bin/resource_windows.go

@@ -16,7 +16,6 @@
 
 //go:generate go run resource_windows.go
 //go:build tools
-// +build tools
 
 package main
 

bin/test_independence.go

@@ -1,5 +1,4 @@
 //go:build ignore
-// +build ignore
 
 // Test that the tests in the suite passed in are independent