i965: disable shadow batches when batch debugging.

If you want to dump batch state, it needs to have the relocs processed
but the relocs don't get processed on the shadow batch.

Choose debugging over speed here.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4846>

src/mesa/drivers/dri/i965/intel_batchbuffer.c

@@ -130,7 +130,11 @@ intel_batchbuffer_init(struct brw_context *brw)
    struct intel_batchbuffer *batch = &brw->batch;
    const struct gen_device_info *devinfo = &screen->devinfo;
 
-   batch->use_shadow_copy = !devinfo->has_llc;
+   if (unlikely(INTEL_DEBUG & DEBUG_BATCH)) {
+      /* The shadow doesn't get relocs written so state decode fails. */
+      batch->use_shadow_copy = false;
+   } else
+      batch->use_shadow_copy = !devinfo->has_llc;
 
    init_reloc_list(&batch->batch_relocs, 250);
    init_reloc_list(&batch->state_relocs, 250);