build: apply gofmt from golang 1.17

backend/qingstor/qingstor.go

@@ -1,6 +1,7 @@
 // Package qingstor provides an interface to QingStor object storage
 // Home: https://www.qingcloud.com/
 
+//go:build !plan9 && !js
 // +build !plan9,!js
 
 package qingstor

backend/qingstor/qingstor_test.go

@@ -1,5 +1,6 @@
 // Test QingStor filesystem interface
 
+//go:build !plan9 && !js
 // +build !plan9,!js
 
 package qingstor

backend/qingstor/qingstor_unsupported.go

@@ -1,6 +1,7 @@
 // Build for unsupported platforms to stop go complaining
 // about "no buildable Go source files "
 
+//go:build plan9 || js
 // +build plan9 js
 
 package qingstor

backend/qingstor/upload.go

@@ -1,5 +1,6 @@
 // Upload object to QingStor
 
+//go:build !plan9 && !js
 // +build !plan9,!js
 
 package qingstor