Totally disable the DFLTCC extension before tests

Author: nobu

Rakefile

@@ -1,16 +1,15 @@
 require "bundler/gem_tasks"
 require "rake/testtask"
 
-desc "Run tests"
-task :test do
+if RUBY_PLATFORM.include?("s390x")
   # Avoid possible test failures with the zlib applying the following patch on
   # s390x CPU architecture.
   # https://github.com/madler/zlib/pull/410
-  ENV["DFLTCC"] = "0" if RUBY_PLATFORM =~ /s390x/
-  Rake::Task["test_internal"].invoke
+  ENV["DFLTCC"] = "0"
 end
 
-Rake::TestTask.new(:test_internal) do |t|
+desc "Run tests"
+Rake::TestTask.new do |t|
   t.libs << "test/lib"
   t.ruby_opts << "-rhelper"
   t.test_files = FileList["test/**/test_*.rb"]