Clang -> XCode 4.3+

Author: jeremy

README.md

@@ -57,7 +57,7 @@ ruby-build provides an `rbenv-install` command that shortens this to:
 
 #### master
 
-* Clang may be used to build 1.9.3-p125 and later
+* XCode 4.3+ may be used to build 1.9.3-p125 and later
 * Added definitions for REE 1.8.7-2012.02 and 1.8.7-2009.10
 * Added definitions for JRuby 1.6.7
 * Added definitions for Ruby 1.9.2-p318 and 1.9.3-p194