fix typo in deprecation warning on config.osx? method

lib/cocoapods/config.rb

@@ -62,7 +62,7 @@ module Pod
     def osx?
       require 'colored'
       caller.find { |line| line =~ /^(.+.podspec):\d*/ }
-      puts "[!] The use of `config.ios?` is deprecated and will be removed in version 0.7.#{" Called from: #{$1}" if $1}".red
+      puts "[!] The use of `config.osx?` is deprecated and will be removed in version 0.7.#{" Called from: #{$1}" if $1}".red
       podfile.target_definitions[:default].platform == :osx if podfile
     end