Update fuzzer build path that was missed in the repo shuffle

BUG=tint:1418

Change-Id: Ie30d9859845b74b36775b56e0dd41ff731a63528
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/81580
Auto-Submit: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Kokoro: Ben Clayton <bclayton@google.com>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
diff --git a/src/tint/fuzzers/tint_ast_fuzzer/BUILD.gn b/src/tint/fuzzers/tint_ast_fuzzer/BUILD.gn
index e9a7f28..036ec8a 100644
--- a/src/tint/fuzzers/tint_ast_fuzzer/BUILD.gn
+++ b/src/tint/fuzzers/tint_ast_fuzzer/BUILD.gn
@@ -30,7 +30,7 @@
       "${tint_root_dir}/src/tint:tint_common_config",
     ]
 
-    include_dirs = [ "${target_gen_dir}/../.." ]
+    include_dirs = [ "${target_gen_dir}/../../../.." ]
 
     deps = [
       ":tint_ast_fuzzer_proto",