Merge pull request #5128 from shuujii/simplify-MRubyCommand-_run-to-avoid-duplicated-compilation

Simplify `MRuby::Command#_run` to avoid duplicated compilation

lib/mruby/build/command.rb

@@ -36,13 +36,7 @@ module MRuby
 
     private
     def _run(options, params={})
-      return sh command + ' ' + ( options % params ) if NotFoundCommands.key? @command
-      begin
-        sh build.filename(command) + ' ' + ( options % params )
-      rescue RuntimeError
-        NotFoundCommands[@command] = true
-        _run options, params
-      end
+      sh "#{build.filename(command)} #{options % params}"
     end
   end