[Core] Update syntax change.

lib/cocoapods/target/pod_target.rb

@@ -67,7 +67,7 @@ module Pod
     # @param [String] build_config Name of the build configuration that caller is unsure if this target should
     #                 be linked with.
     def include_in_build_config?(build_config)
-      @target_definition.is_pod_whitelisted_for_configuration?(@specs[0].name, build_config)
+      @target_definition.pod_whitelisted_for_configuration?(@specs[0].name, build_config)
     end
 
   end