[libcxx] [test] Remove a leftover unused function in config.py. NFC.

[mstorsjo]

Summary

While there's little value in polishing the old config system,
I ran into this function and was confused for a while, while grepping
around and trying to wrap my head around things.

libcxx/utils/libcxx/test/config.py

def print_config_info(self):
             if k not in os.environ or os.environ[k] != v:
                 show_env_vars[k] = v
         self.lit_config.note('Adding environment variables: %r' % show_env_vars)
         self.lit_config.note("Linking against the C++ Library at {}".format(self.cxx_library_root))
         self.lit_config.note("Running against the C++ Library at {}".format(self.cxx_runtime_root))
         self.lit_config.note("Linking against the ABI Library at {}".format(self.abi_library_root))
         self.lit_config.note("Running against the ABI Library at {}".format(self.abi_runtime_root))
 
-    def get_test_format(self):
-        from libcxx.test.format import LibcxxTestFormat
-        return LibcxxTestFormat(
-            self.cxx,
-            self.use_clang_verify,
-            self.executor,
-            exec_env=self.exec_env)
-
     def configure_cxx(self):
         # Gather various compiler parameters.
         cxx = self.get_lit_conf('cxx_under_test')
         self.cxx_is_clang_cl = cxx is not None and \
                                os.path.basename(cxx).startswith('clang-cl')
         # If no specific cxx_under_test was given, attempt to infer it as
         # clang++.
         if cxx is None or self.cxx_is_clang_cl: