Remove supports_dynamic_linker_feature from macOS unix crosstool

This feature isn't supported on macOS, and it isn't part of the Xcode CC
toolchain, but it is left over here from when it was supported in the
past.

bazelbuild@ec55533

Fixes: bazelbuild#16414 (comment)

tools/cpp/unix_cc_toolchain_config.bzl

@@ -1383,7 +1383,6 @@ def _impl(ctx):
             user_link_flags_feature,
             default_link_libs_feature,
             fdo_optimize_feature,
-            supports_dynamic_linker_feature,
             dbg_feature,
             opt_feature,
             user_compile_flags_feature,