extconf.rb in io-console-0.5.6

- old
+ new

@@ -1,9 +1,9 @@
 # frozen_string_literal: false
 require 'mkmf'
 
-ok = true
+ok = true if RUBY_ENGINE == "ruby"
 hdr = nil
 case
 when macro_defined?("_WIN32", "")
   # rb_w32_map_errno: 1.8.7
   vk_header = File.exist?("#$srcdir/win32_vk.list") ? "chksum" : "inc"
@@ -12,12 +12,13 @@
   have_func("cfmakeraw", hdr)
 when have_header(hdr = "sgtty.h")
   %w"stty gtty".each {|f| have_func(f, hdr)}
 else
   ok = false
-end
-if ok
+end if ok
+case ok
+when true
   have_header("sys/ioctl.h") if hdr
   # rb_check_hash_type: 1.9.3
   # rb_io_get_write_io: 1.9.1
   # rb_cloexec_open: 2.0.0
   # rb_funcallv: 2.1.0
@@ -25,6 +26,8 @@
   # rb_sym2str: 2.2.0
   $defs << "-D""ENABLE_IO_GETPASS=1"
   create_makefile("io/console") {|conf|
     conf << "\n""VK_HEADER = #{vk_header}\n"
   }
+when nil
+  File.write("Makefile", dummy_makefile($srcdir).join(""))
 end