GN: Use updated path to libtint.

Bug: dawn:706
Change-Id: I39864f75b12272992bd9129a8eeea1ac6479a99e
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/44764
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>
Auto-Submit: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>

src/dawn_native/BUILD.gn

@@ -627,7 +627,7 @@ source_set("dawn_native_sources") {
   }
 
   if (dawn_enable_wgsl) {
-    deps += [ "${dawn_tint_dir}:libtint" ]
+    deps += [ "${dawn_tint_dir}/src:libtint" ]
   }
 }