zink: only save frag const buffers when used by blit

fixes upload manager constant buffer leak.
zink only needs to save the const buffer for stencil fallback blits.

cc: mesa-stable

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21134>

src/gallium/drivers/zink/zink_blit.c

@@ -355,7 +355,7 @@ zink_blit(struct pipe_context *pctx,
       util_blitter_clear_depth_stencil(ctx->blitter, dst_view, PIPE_CLEAR_STENCIL,
                                        0, 0, info->dst.box.x, info->dst.box.y,
                                        info->dst.box.width, info->dst.box.height);
-      zink_blit_begin(ctx, ZINK_BLIT_SAVE_FB | ZINK_BLIT_SAVE_FS | ZINK_BLIT_SAVE_TEXTURES);
+      zink_blit_begin(ctx, ZINK_BLIT_SAVE_FB | ZINK_BLIT_SAVE_FS | ZINK_BLIT_SAVE_TEXTURES | ZINK_BLIT_SAVE_FS_CONST_BUF);
       util_blitter_stencil_fallback(ctx->blitter,
                                     info->dst.resource,
                                     info->dst.level,
@@ -390,8 +390,10 @@ zink_blit_begin(struct zink_context *ctx, enum zink_blit_flags flags)
    util_blitter_save_rasterizer(ctx->blitter, ctx->rast_state);
    util_blitter_save_so_targets(ctx->blitter, ctx->num_so_targets, ctx->so_targets);
 
-   if (flags & ZINK_BLIT_SAVE_FS) {
+   if (flags & ZINK_BLIT_SAVE_FS_CONST_BUF)
       util_blitter_save_fragment_constant_buffer_slot(ctx->blitter, ctx->ubos[MESA_SHADER_FRAGMENT]);
+
+   if (flags & ZINK_BLIT_SAVE_FS) {
       util_blitter_save_blend(ctx->blitter, ctx->gfx_pipeline_state.blend_state);
       util_blitter_save_depth_stencil_alpha(ctx->blitter, ctx->dsa_state);
       util_blitter_save_stencil_ref(ctx->blitter, &ctx->stencil_ref);

src/gallium/drivers/zink/zink_types.h

@@ -135,6 +135,7 @@ enum zink_blit_flags {
    ZINK_BLIT_SAVE_FB = 1 << 2,
    ZINK_BLIT_SAVE_TEXTURES = 1 << 3,
    ZINK_BLIT_NO_COND_RENDER = 1 << 4,
+   ZINK_BLIT_SAVE_FS_CONST_BUF = 1 << 5,
 };
 
 /* descriptor types; also the ordering of the sets