[OoT] fix draw layer suffix always being present

[Dragorn421]

Context

OoT DList exporter

Fast64 allows setting draw layers by material. This splits the mesh by material on export, between opaque/translucent/overlay draw layers, writing out different display lists.

It was reported last year #602 that fast64 however was writing those different display lists using the same name, obviously causing errors on compile due to the duplicate symbol name.

The issue was fixed in #605 by appending a "_drawlayer_dl" suffix to the written draw layer display list

However there have been complaints since then about this behavior since you can't name a single-draw-layer-using mesh properly (like gMyCubeDL) and have it be exported under that name, it would export as eg gMyCubeDL_opaque_dl

This PR

This PR makes the suffix be omitted when a mesh is composed of a single draw layer. When several draw layers are present, it uses the draw layer suffixes.

Testing

I tested:

• DL export with a single draw layer
• DL export with two draw layers
• deku tree import-export
• gerudo skeleton import-export
• epona skinskeleton import-export

[Trueffeloot]

DL exporting works as it should. I didn't try the other things like importing and exporting a scene though because I don't know how these files should be looking afterwards.