[libc][bazel] Export .bzl files for libc/test and libc/test/src/math.

Author: lntue

utils/bazel/llvm-project-overlay/libc/test/BUILD.bazel

@@ -1,3 +1,7 @@
 # This file is licensed under the Apache License v2.0 with LLVM Exceptions.
 # See https://llvm.org/LICENSE.txt for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+package(default_visibility = ["//visibility:public"])
+
+exports_files(["libc_test_rules.bzl"])

utils/bazel/llvm-project-overlay/libc/test/src/math/BUILD.bazel

@@ -8,6 +8,8 @@ load("//libc/test/src/math:libc_math_test_rules.bzl", "math_test")
 
 package(default_visibility = ["//visibility:public"])
 
+exports_files(["libc_math_test_rules.bzl"])
+
 licenses(["notice"])
 
 math_test(