Add hfrag, clean up some background renderer stuff (#3509)

This adds hfrag, but with a few remaining issues:
- The textures aren't animated. Instead, it just uses one texture.
- The texture filtering isn't as good as at it could be.

I also cleaned up a few issues with the background renderers:
- Cleaned up some stuff that is common to hfrag, tie, tfrag, shrub
- Moved time-of-day color packing stuff to FR3 creation, rather than at
level load. This appears to reduce the frame time spikes when a level is
first drawn by about 5 or 6 ms in big levels.
- Cleaned up the x86 specific stuff used in time of day. Now there's
only one place where we have an `ifdef`, rather than spreading it all
over the rendering code.

decompiler/util/data_decompile.cpp

@@ -1233,7 +1233,10 @@ goos::Object decompile_structure(const TypeSpec& type,
         auto len = field.array_size();
         auto stride = ts.get_size_in_type(field) / len;
         ASSERT(stride == field_type_info->get_size_in_memory());
-
+        if (field.type() == TypeSpec("int128") || field.type() == TypeSpec("uint128")) {
+          lg::die("Trying to decompile field {} of {} as an array of type {} not supported",
+                  field.name(), type_info->get_name(), field.type().print());
+        }
         field_defs_out.emplace_back(
             field.name(), decompile_value_array(field.type(), field_type_info, len, stride,
                                                 field_start, obj_words, ts));