[libc][Bazel] Add errno dependency to tests.

utils/bazel/llvm-project-overlay/libc/test/libc_test_rules.bzl

Args:
       libc_function_deps: List of libc_function targets used by this test.
       deps: The list of other libraries to be linked in to the test target.
       **kwargs: Attributes relevant for a cc_test. For example, name, srcs.
     """
     native.cc_test(
         name = name,
         srcs = srcs,
         deps = [d + INTERNAL_SUFFIX for d in libc_function_deps] + [
+            "//libc:errno",
             "//libc:libc_root",
             "//libc/test/UnitTest:LibcUnitTest",
         ] + deps,
         features = ["-link_llvmlibc"],  # Do not link libllvmlibc.a
         **kwargs
     )