Stop disabling link_llvmlibc feature in libc_test Bazel rule

This detail is not relevant for the upstream Bazel version. llvm-libc unit tests today directly invoke the function under test using the namespace, which reduces the potential problems of linking with some other (system-provided) version of llvm-libc further.

Author: vonosmas

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

@@ -36,7 +36,6 @@ def libc_test(name, srcs, libc_function_deps = [], copts = [], deps = [], local_
             "//libc/test/UnitTest:LibcUnitTest",
             "//libc:__support_macros_config",
         ] + deps,
-        features = ["-link_llvmlibc"],  # Do not link libllvmlibc.a
         copts = copts + libc_common_copts(),
         linkstatic = 1,
         **kwargs