[libc++][NFC] Remove non-existant macros from the clang-format file

These macros existed at some point in libc++, but have been removed now,
so we can also remove them from the clang-format file.

Author: philnik777

libcxx/.clang-format

@@ -30,15 +30,13 @@ AttributeMacros: [
                   '_LIBCPP_DEPRECATED_IN_CXX20',
                   '_LIBCPP_DEPRECATED_IN_CXX23',
                   '_LIBCPP_DEPRECATED',
-                  '_LIBCPP_DISABLE_EXTENTSION_WARNING',
                   '_LIBCPP_EXCLUDE_FROM_EXPLICIT_INSTANTIATION',
                   '_LIBCPP_EXPORTED_FROM_ABI',
                   '_LIBCPP_EXTERN_TEMPLATE_TYPE_VIS',
                   '_LIBCPP_FALLTHROUGH',
                   '_LIBCPP_HIDDEN',
                   '_LIBCPP_HIDE_FROM_ABI_AFTER_V1',
                   '_LIBCPP_HIDE_FROM_ABI',
-                  '_LIBCPP_INTERNAL_LINKAGE',
                   '_LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS',
                   '_LIBCPP_NO_SANITIZE',
                   '_LIBCPP_NO_UNIQUE_ADDRESS',