[lavapipe] Add wsi:stub target.

Change-Id: I753a9f15fb7f367fafaff4d0fbd0fdc6ddda3494
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/mesa/+/990367
Reviewed-by: Josh Gargus <jjosh@google.com>
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/mesa/+/1005914
Reviewed-by: Alice Neels <neelsa@google.com>
Commit-Queue: Josh Gargus <jjosh@google.com>
diff --git a/src/vulkan/wsi/BUILD.gn b/src/vulkan/wsi/BUILD.gn
index ec1a35a..43eacea 100644
--- a/src/vulkan/wsi/BUILD.gn
+++ b/src/vulkan/wsi/BUILD.gn
@@ -59,6 +59,26 @@
   ]
 }
 
+# For non-Linux platforms.
+mesa_source_set("stub") {
+  public_configs = [ ":wsi_config" ]
+  public_deps = [ "$mesa_build_root/src/vulkan/util" ]
+  deps = [
+    ":wsi_entrypoints",
+    "$mesa_build_root/src/util:headers",
+  ]
+  sources = [
+    "$target_gen_dir/wsi_common_entrypoints.c",
+    "$target_gen_dir/wsi_common_entrypoints.h",
+    "wsi_common.c",
+    "wsi_common.h",
+  ]
+
+  include_dirs = [ "$target_gen_dir", "$mesa_build_root/src/vulkan/runtime" ]
+
+  configs = [ "//build/config:Wno-conversion" ]
+}
+
 mesa_source_set("wsi") {
   public_configs = [ ":wsi_config" ]
   public_deps = [ "$mesa_build_root/src/vulkan/util" ]