Fix T74096: Paint Masking overlay can`t be hidden

Caused by rB9516921c05bd.

Dont really see a reason to draw overlays here if overlays are disabled.
Looks like this only affects Face/Vertex mask selection drawing [which
should indeed be hidden when overlays are disabled] next to two
exceptions:

- OVERLAY_paint_vertex_cache_populate draws weights as well [D7176 /
T70807 might be related here, but to me it looks like drawing weights
here is actually not needed at all]

- OVERLAY_paint_texture_cache_populate calls
DRW_cache_mesh_surface_texpaint_get [not sure about this one, this is
also called from workbench_cache_texpaint_populate, looks like this is
not needed when overlays are hidden]

Maniphest Tasks: T74096

Differential Revision: https://developer.blender.org/D7179

source/blender/draw/engines/overlay/overlay_engine.c

@@ -304,7 +304,7 @@ static void OVERLAY_cache_populate(void *vedata, Object *ob)
   else if (in_pose_mode && draw_bones) {
     OVERLAY_pose_armature_cache_populate(vedata, ob);
   }
-  else if (in_paint_mode) {
+  else if (in_paint_mode && !pd->hide_overlays) {
     switch (draw_ctx->object_mode) {
       case OB_MODE_VERTEX_PAINT:
         OVERLAY_paint_vertex_cache_populate(vedata, ob);