Do not force `[system]` value for custom module maps

lib/cocoapods/installer/xcode/pods_project_generator/pod_target_installer.rb

@@ -625,7 +625,7 @@ module Pod
             UI.message "- Copying module map file to #{UI.path(path)}" do
               contents = custom_module_map.read
               unless target.requires_frameworks?
-                contents.gsub!(/^(\s*)framework\s+(module[^{}]+){/, '\1\2[system] {')
+                contents.gsub!(/^(\s*)framework\s+(module[^{}]+){/, '\1\2{')
               end
               generator = Generator::Constant.new(contents)
               update_changed_file(generator, path)

cocoapods-integration-specs @ f775f8d2

-Subproject commit 482395da30d5fc55872498d471f2173dc94e8331
+Subproject commit f775f8d2792fa04bf0bfef570c83cf0f7afa802c