[bazel] Port #92983 (#93874)

Author: keith

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

@@ -112,6 +112,8 @@ cc_test(
         "//llvm:BitstreamReader",
         "//llvm:BitstreamWriter",
         "//llvm:Support",
+        "//llvm:TestingSupport",
+        "//third-party/unittest:gmock",
         "//third-party/unittest:gtest",
         "//third-party/unittest:gtest_main",
     ],