Only check constant leaks by default for `make test-spec`

* See https://github.com/ruby/ruby/pull/9548

spec/default.mspec

@@ -4,8 +4,8 @@ if (opt = ENV["RUBYOPT"]) and (opt = opt.dup).sub!(/(?:\A|\s)-w(?=\z|\s)/, '')
   ENV["RUBYOPT"] = opt
 end
 
-# Enable leakcheckers by ruby/mspec
-ENV["CHECK_LEAKS"] ||= "true"
+# Enable constant leak checks by ruby/mspec
+ENV["CHECK_CONSTANT_LEAKS"] ||= "true"
 
 require "./rbconfig" unless defined?(RbConfig)
 require_relative "../tool/test-coverage" if ENV.key?("COVERAGE")

spec/mspec/lib/mspec/runner/formatters/base.rb

@@ -5,6 +5,9 @@ require 'mspec/utils/options'
 
 if ENV['CHECK_LEAKS']
   require 'mspec/runner/actions/leakchecker'
+end
+
+if ENV['CHECK_LEAKS'] || ENV['CHECK_CONSTANT_LEAKS']
   require 'mspec/runner/actions/constants_leak_checker'
 end
 
@@ -40,8 +43,11 @@ class BaseFormatter
     @counter = @tally.counter
 
     if ENV['CHECK_LEAKS']
-      save = ENV['CHECK_LEAKS'] == 'save'
       LeakCheckerAction.new.register
+    end
+
+    if ENV['CHECK_LEAKS'] || ENV['CHECK_CONSTANT_LEAKS']
+      save = ENV['CHECK_LEAKS'] == 'save' || ENV['CHECK_CONSTANT_LEAKS'] == 'save'
       ConstantsLeakCheckerAction.new(save).register
     end