Make D3D12 Fuzzer Only Build On Windows

Prevents the d3d12 fuzzer from building on non-windows platforms.

bug: dawn:444
bug: chromium:1094230
Change-Id: I3ce20c645b3fe99b51e06b493ced34308d7cc21e
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/23162
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Brandon Jones <brandon1.jones@intel.com>

src/fuzzers/BUILD.gn

diff --git a/src/fuzzers/BUILD.gn b/src/fuzzers/BUILD.gn
index c157b0a..6d3cc01 100644
--- a/src/fuzzers/BUILD.gn
+++ b/src/fuzzers/BUILD.gn
@@ -142,12 +142,14 @@
   additional_configs = [ "${dawn_root}/src/common:dawn_internal" ]
 }
 
-dawn_fuzzer_test("dawn_wire_server_and_d3d12_backend_fuzzer") {
-  sources = [ "DawnWireServerAndD3D12BackendFuzzer.cpp" ]
+if (is_win) {
+  dawn_fuzzer_test("dawn_wire_server_and_d3d12_backend_fuzzer") {
+    sources = [ "DawnWireServerAndD3D12BackendFuzzer.cpp" ]
 
-  deps = [ ":dawn_wire_server_fuzzer_common" ]
+    deps = [ ":dawn_wire_server_fuzzer_common" ]
 
-  additional_configs = [ "${dawn_root}/src/common:dawn_internal" ]
+    additional_configs = [ "${dawn_root}/src/common:dawn_internal" ]
+  }
 }
 
 dawn_fuzzer_test("dawn_wire_server_and_vulkan_backend_fuzzer") {
@@ -168,8 +170,11 @@
     ":dawn_spvc_glsl_fast_fuzzer",
     ":dawn_spvc_hlsl_fast_fuzzer",
     ":dawn_spvc_msl_fast_fuzzer",
-    ":dawn_wire_server_and_d3d12_backend_fuzzer",
     ":dawn_wire_server_and_frontend_fuzzer",
     ":dawn_wire_server_and_vulkan_backend_fuzzer",
   ]
+
+  if (is_win) {
+    deps += [":dawn_wire_server_and_d3d12_backend_fuzzer"]
+  }
 }