Fix missing AU, VST, and Ladspa effects

This also prevents a link error if you specifically link against the
10.9 SDK or older.

CMakeLists.txt

@@ -45,6 +45,9 @@ elseif( APPLE )
    set( CMAKE_OSX_SYSROOT macosx CACHE INTERNAL "" )
    set( CMAKE_XCODE_ATTRIBUTE_CODE_SIGN_IDENTITY "" CACHE INTERNAL "" )
 
+   # This prevents a link error when building with the 10.9 or older SDKs
+   set( CMAKE_XCODE_ATTRIBUTE_CLANG_LINK_OBJC_RUNTIME OFF )
+
    # Shouldn't cmake do this???
    string( APPEND CMAKE_CXX_FLAGS " -stdlib=libc++" )
 endif()