[bazel][clang] Add missing dependency for 8b5d3ba

Author: d0k

utils/bazel/llvm-project-overlay/clang/unittests/BUILD.bazel

@@ -134,6 +134,7 @@ cc_test(
         "//clang:ast",
         "//clang:ast_matchers",
         "//clang:basic",
+        "//clang:frontend",
         "//clang:lex",
         "//clang:serialization",
         "//clang:testing",