Take into account wxAnimationCtrl "animation" property in wxrc.

The files used as the values of this property need to be included in the
generated file too.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@77004 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775