merge revision(s) 45518: [Backport #9702]

	* ext/readline/extconf.rb (rl_hook_func_t): check pointer type.
	  [ruby-dev:48089] [Bug #9702]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@45754 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
revert r45747 because it introduced severe incompatibility.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@45755 b2dd03c8-39d4-4d8f-98ff-823fe69b080e