RubyVM::MJIT is deprecated, prefer RubyVM::JIT now

Author: nobu

test/net/http/test_httpresponse.rb

@@ -78,7 +78,9 @@ def test_read_body_block
 
   def test_read_body_block_mod
     # http://ci.rvm.jp/results/trunk-mjit-wait@silicon-docker/3019353
-    skip 'too unstable with --jit-wait, and extending read_timeout did not help it' if defined?(RubyVM::MJIT) && RubyVM::MJIT.enabled?
+    if defined?(RubyVM::JIT) && RubyVM::JIT.enabled? || defined?(RubyVM::MJIT) && RubyVM::MJIT.enabled?
+      skip 'too unstable with --jit-wait, and extending read_timeout did not help it'
+    end
     IO.pipe do |r, w|
       buf = 'x' * 1024
       buf.freeze