extconf.rb: rl_hook_func_t for old readline

* ext/readline/extconf.rb (rl_hook_func_t): define as Function for
  very old readline versions.  [ruby-core:61209] [Bug #9578]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45240 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Sun Mar  2 11:13:30 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ext/readline/extconf.rb (rl_hook_func_t): define as Function for
+	  very old readline versions.  [ruby-core:61209] [Bug #9578]
+
 Sun Mar  2 10:56:12 2014  Zachary Scott  <e@zzak.io>
 
 	* README.EXT: [DOC] Remove needless char

ext/readline/extconf.rb

@@ -19,6 +19,10 @@ def readline.have_func(func)
   return super(func, headers)
 end
 
+def readline.have_type(type)
+  return super(type, headers)
+end
+
 dir_config('curses')
 dir_config('ncurses')
 dir_config('termcap')
@@ -94,4 +98,8 @@ readline.have_func("clear_history")
 readline.have_func("rl_redisplay")
 readline.have_func("rl_insert_text")
 readline.have_func("rl_delete_text")
+unless readline.have_type("rl_hook_func_t")
+  $DEFS << "-Drl_hook_func_t=Function"
+end
+
 create_makefile("readline")