Code Quality: Replace for loops with LISTBASE_FOREACH

Note this only changes cases where the variable was declared inside
the for loop. To handle it outside as well is a different challenge.

Differential Revision: https://developer.blender.org/D7320

source/blender/editors/space_buttons/space_buttons.c

@@ -312,7 +312,7 @@ static void buttons_navigation_bar_region_init(wmWindowManager *wm, ARegion *reg
 
 static void buttons_navigation_bar_region_draw(const bContext *C, ARegion *region)
 {
-  for (PanelType *pt = region->type->paneltypes.first; pt; pt = pt->next) {
+  LISTBASE_FOREACH (PanelType *, pt, &region->type->paneltypes) {
     pt->flag |= PNL_LAYOUT_VERT_BAR;
   }