[spv] Color output handling in SPIR-V emission.

src/shader_recompiler/backend/spirv/spirv_emit_context.h

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -244,6 +247,7 @@ public:
 
     Id output_f32{};
     Id output_u32{};
+    Id output_s32{};
 
     Id image_buffer_type{};
     Id image_u32{};