[Vulkan] add no_discard_stencil_in_transfer_pipelines support

src/xenia/gpu/vulkan/vulkan_render_target_cache.cc

@@ -19,6 +19,7 @@
 #include "xenia/base/logging.h"
 #include "xenia/base/math.h"
 #include "xenia/gpu/draw_util.h"
+#include "xenia/gpu/gpu_flags.h"
 #include "xenia/gpu/registers.h"
 #include "xenia/gpu/spirv_builder.h"
 #include "xenia/gpu/spirv_compatibility.h"
@@ -4281,7 +4282,7 @@ VkShaderModule VulkanRenderTargetCache::GetTransferShader(
         }
       } break;
       case TransferOutput::kStencilBit: {
-        if (packed) {
+        if (packed && !cvars::no_discard_stencil_in_transfer_pipelines) {
           // Kill the sample if the needed stencil bit is not set.
           assert_true(push_constants_member_stencil_mask != UINT32_MAX);
           id_vector_temp.clear();