Refine dependencies for `mruby-config`

mrbgems/mruby-bin-config/mrbgem.rake

@@ -8,13 +8,14 @@ unless MRuby::Build.current.kind_of?(MRuby::CrossBuild)
     mruby_config = name + (ENV['OS'] == 'Windows_NT' ? '.bat' : '')
     mruby_config_path = "#{build.build_dir}/bin/#{mruby_config}"
     make_cfg = "#{build.build_dir}/lib/libmruby.flags.mak"
+    tmplt_path = "#{__dir__}/#{mruby_config}"
     build.bins << mruby_config
 
-    file mruby_config_path => [build.libmruby_static, make_cfg] do |t|
-      config = Hash[File.readlines(make_cfg).map(&:chomp).map {|l|
+    file mruby_config_path => [make_cfg, tmplt_path] do |t|
+      config = Hash[File.readlines(make_cfg).map!(&:chomp).map! {|l|
         l.gsub('\\"', '"').split(' = ', 2).map! {|s| s.sub(/^(?=.)/, 'echo ')}
       }]
-      tmplt = File.read("#{__dir__}/#{mruby_config}")
+      tmplt = File.read(tmplt_path)
       File.write(t.name, tmplt.gsub(/(#{Regexp.union(*config.keys)})\b/, config))
       FileUtils.chmod(0755, t.name)
     end