Blender Git Loki

Fix T71495: Some Textures with AnimData not visible in Dopesheet

T71495 describes two problems with animation of textures not showing up in
the dope sheet:

1. textures connected to force fields
2. textures of brushes

This patch resolves the first case.

An alternative would be to switch to iteration of dependencies using
`BKE_library_foreach_ID_link()`. This is a good idea to do at some point,
but adding these few lines was considerably easier & safer to do.