Sort flag sets so exported C is reproducible

[Taldariner]

Problem

Exporting the same scene twice can produce different C files, with nothing changed in the blend file. Only the order of flags inside a command differs:

-	gsSPClearGeometryMode(G_SHADING_SMOOTH | G_LIGHTING),
+	gsSPClearGeometryMode(G_LIGHTING | G_SHADING_SMOOTH),

Reproduction, run it a few times (each run is a fresh process):

blender -b --python-expr "import addon_utils; addon_utils.enable('fast64'); from fast64.fast64_internal.f3d.f3d_gbi import SPClearGeometryMode; print(SPClearGeometryMode({'G_LIGHTING','G_SHADING_SMOOTH'}).to_c())"

On my machine 6 runs printed G_LIGHTING | G_SHADING_SMOOTH five times and G_SHADING_SMOOTH | G_LIGHTING once. Exporting a corpus of test meshes, 8 runs of the same export produced 2 distinct sets of files.

This matters when an export is diffed against what is already committed in a decomp repo: the diff shows changes that are not changes. It also makes it impossible to confirm that a change to the exporter left the output alone, which is what I ran into while working on f3d_writer.py.

Cause

GbiMacro.getattr_virtual joins iterable fields with " | " in iteration order, and several macros keep their flags in a set. Python randomizes string hashes per process, so the iteration order of a set of flag names changes from run to run.

Fix

Sort the values when the field is a set or frozenset. Lists keep their order, so nothing positional is affected.

This is safe for every field it touches, because they are flag unions that to_binary ORs into a single word:

Macro	Field
SPGeometryMode	clearFlagList, setFlagList
SPSetGeometryMode	flagList
SPClearGeometryMode	flagList
SPLoadGeometryMode	flagList
DPSetOtherMode	mode0, mode1

DPSetRenderMode has its own positional to_c and is not affected. Binary output never depended on the order.

Import is unaffected as well: f3d_parser splits flag lists on | and does not care about order.

Verification

A corpus of 22 generated meshes (flat and smooth, vertex colors, fog, UV seams, large texture mode, F3DEX3 packed normals and cel shading) exported to C for F3D, F3DEX2 and F3DEX3, plus a skinned geolayout export, on Blender 4.2.16 LTS:

• before the change, 8 runs of the same export produced 2 distinct outputs; after it, 1;
• comparing the two trees, 130 files are identical except for 8 reordered flag commands, and the sorted output matches one of the orders the current code already emits;
• to_binary output is identical for both orders of the same flags, for every affected macro in F3D, F3DEX, F3DEX2 and F3DEX3.