Chore: Remove ctlcmd and leftover envvar (#5392)

https://github.com/v2fly/v2ray-core/issues/360

main/confloader/confloader.go

@@ -10,12 +10,10 @@ import (
 
 type (
 	configFileLoader func(string) (io.Reader, error)
-	extconfigLoader  func([]string, io.Reader) (io.Reader, error)
 )
 
 var (
 	EffectiveConfigFileLoader configFileLoader
-	EffectiveExtConfigLoader  extconfigLoader
 )
 
 // LoadConfig reads from a path/url/stdin
@@ -27,13 +25,3 @@ func LoadConfig(file string) (io.Reader, error) {
 	}
 	return EffectiveConfigFileLoader(file)
 }
-
-// LoadExtConfig calls xctl to handle multiple config
-// the actual work also in external module
-func LoadExtConfig(files []string, reader io.Reader) (io.Reader, error) {
-	if EffectiveExtConfigLoader == nil {
-		return nil, errors.New("external config module not loaded").AtError()
-	}
-
-	return EffectiveExtConfigLoader(files, reader)
-}