fake.rb: fix RUBY_DESCRIPTION for MJIT

* template/fake.rb.in: switch RUBY_DESCRIPTION at runtime
  depending on the MJIT status.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63523 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

template/fake.rb.in

@@ -15,7 +15,7 @@ if inc = arg['i']
     scan(/rb_define_global_const\("(RUBY_\w+)",[^;]*?\bMK(?:INT|STR)\(([^()]*)\)/m) do |n, v|
     version[n] = src.value(v)
   end
-  version['RUBY_DESCRIPTION'] = src.value('description_with_jit') if RubyVM::MJIT.enabled?
+  arg['RUBY_DESCRIPTION_WITH_JIT'] = src.value('description_with_jit')
 end
 %>baseruby="<%=arg['BASERUBY']%>"
 _\
@@ -32,7 +32,9 @@ class Object
   CROSS_COMPILING = RUBY_PLATFORM
   constants.grep(/^RUBY_/) {|n| remove_const n}
 % arg['versions'].each  {|n, v|
-  <%=n%> = <%=v.inspect%>
+  <%=n%> = <%if n=='RUBY_DESCRIPTION' %>RubyVM::MJIT.enabled? ?
+    <%=arg['RUBY_DESCRIPTION_WITH_JIT'].inspect%> :
+    <%end%><%=v.inspect%>
 % }
 end
 builddir = File.dirname(File.expand_path(__FILE__))