Cleanup: Remove scene frame macros (`CFRA` et al.)

Removes the following macros for scene/render frame values:
- `CFRA`
- `SUBFRA`
- `SFRA`
- `EFRA`

These macros don't add much, other than saving a few characters when typing.
It's not immediately clear what they refer to, they just hide what they
actually access. Just be explicit and clear about that.
Plus these macros gave read and write access to the variables, so eyesores like
this would be done (eyesore because it looks like assigning to a constant):
```
CFRA = some_frame_nbr;
```

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D15311

1 files changed, 3 insertions, 3 deletions

diff --git a/source/blender/editors/space_clip/clip_editor.c b/source/blender/editors/space_clip/clip_editor.c
index cf7c3b51ae3..9a690f36aab 100644
--- a/source/blender/editors/space_clip/clip_editor.c
+++ b/source/blender/editors/space_clip/clip_editor.c
@@ -1046,7 +1046,7 @@ static int prefetch_get_start_frame(const bContext *C)
 {
   Scene *scene = CTX_data_scene(C);
 
-  return SFRA;
+  return scene->r.sfra;
 }
 
 static int prefetch_get_final_frame(const bContext *C)
@@ -1057,10 +1057,10 @@ static int prefetch_get_final_frame(const bContext *C)
   int end_frame;
 
   /* check whether all the frames from prefetch range are cached */
-  end_frame = EFRA;
+  end_frame = scene->r.efra;
 
   if (clip->len) {
-    end_frame = min_ii(end_frame, SFRA + clip->len - 1);
+    end_frame = min_ii(end_frame, scene->r.sfra + clip->len - 1);
   }
 
   return end_frame;