patch-demo_CMakeLists.txt

--- demo/CMakeLists.txt.orig	2015-08-29 18:52:41 UTC
+++ demo/CMakeLists.txt
@@ -40,6 +40,10 @@ if(NOT MSVC)
   list(APPEND chipmunk_demos_libraries m)
 endif(NOT MSVC)
 
+if(NOT APPLE AND FORCE_CLANG_BLOCKS)
+  list(APPEND chipmunk_demos_libraries BlocksRuntime)
+endif(NOT APPLE AND FORCE_CLANG_BLOCKS)
+
 file(GLOB chipmunk_demos_source_files "*.c")
 
 include_directories(${chipmunk_demos_include_dirs})