tint_wgsl_fuzzer: only depend on dxc if dawn_use_built_dxc

Fixes tint_wgsl_fuzzer failing to run because the loader would look for
the dxcompiler library, even when dawn_use_built_dxc was disabled.

Bug: 409071579
Change-Id: I2205a75d74fc495ae15f56a5fcd0c095427f3a20
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/239254
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>

src/tint/BUILD.gn

diff --git a/src/tint/BUILD.gn b/src/tint/BUILD.gn
index 3e8256f..15944bf 100644
--- a/src/tint/BUILD.gn
+++ b/src/tint/BUILD.gn
@@ -29,6 +29,7 @@
 
 import("//build_overrides/build.gni")
 
+import("../../scripts/dawn_features.gni")
 import("../../scripts/dawn_overrides_with_defaults.gni")
 import("../../scripts/tint_overrides_with_defaults.gni")
 
@@ -303,7 +304,7 @@
 }
 
 source_set("dxcompiler-for-fuzzer") {
-  if (defined(use_libfuzzer) && use_libfuzzer &&
+  if (dawn_use_built_dxc && defined(use_libfuzzer) && use_libfuzzer &&
       (is_win || is_linux || is_mac) && target_cpu != "x86") {
     public_deps = [ "${dawn_dxc_dir}/../gn/dxc:dxcompiler" ]
   }