[clang] Make config-related options CoreOptions

[mgorny]

Summary

Make --config, --no-default-config and --config-*-dir CoreOptions
to enable their availability to all clang driver modes. This improves
consistency given that the default set of configuration files is
processed independently of mode anyway.

[MaskRay]

Thanks!

[MaskRay]

They don't need to be NoXarchOption if I am not mistaken.

[mgorny]

In D134191#3799841, @MaskRay wrote:

They don't need to be NoXarchOption if I am not mistaken.

I don't know about that. The comment on top says "The option is a "driver"-only option, and should not be forwarded to other tools via -Xarch options.". Well, it's processed by driver only, isn't it?

clang/include/clang/Driver/Options.td

 def cl_ext_EQ : CommaJoined<["-"], "cl-ext=">, Group<opencl_Group>, Flags<[CC1Option]>,
   HelpText<"OpenCL only. Enable or disable OpenCL extensions/optional features. The argument is a comma-separated "
            "sequence of one or more extension names, each prefixed by '+' or '-'.">,
   MarshallingInfoStringVector<TargetOpts<"OpenCLExtensionsAsWritten">>;
 
 def client__name : JoinedOrSeparate<["-"], "client_name">;
 def combine : Flag<["-", "--"], "combine">, Flags<[NoXarchOption, Unsupported]>;
 def compatibility__version : JoinedOrSeparate<["-"], "compatibility_version">;
-def config : Separate<["--"], "config">, Flags<[NoXarchOption]>,
+def config : Separate<["--"], "config">, Flags<[NoXarchOption, CoreOption]>,
   HelpText<"Specifies configuration file">;
-def no_default_config : Flag<["--"], "no-default-config">, Flags<[NoXarchOption]>,
+def no_default_config : Flag<["--"], "no-default-config">, Flags<[NoXarchOption, CoreOption]>,
   HelpText<"Disable loading default configuration files">;
-def config_system_dir_EQ : Joined<["--"], "config-system-dir=">, Flags<[NoXarchOption, HelpHidden]>,
+def config_system_dir_EQ : Joined<["--"], "config-system-dir=">, Flags<[NoXarchOption, CoreOption, HelpHidden]>,
   HelpText<"System directory for configuration files">;
-def config_user_dir_EQ : Joined<["--"], "config-user-dir=">, Flags<[NoXarchOption, HelpHidden]>,
+def config_user_dir_EQ : Joined<["--"], "config-user-dir=">, Flags<[NoXarchOption, CoreOption, HelpHidden]>,
   HelpText<"User directory for configuration files">;
 def coverage : Flag<["-", "--"], "coverage">, Group<Link_Group>, Flags<[CoreOption]>;
 def cpp_precomp : Flag<["-"], "cpp-precomp">, Group<clang_ignored_f_Group>;
 def current__version : JoinedOrSeparate<["-"], "current_version">;
 def cxx_isystem : JoinedOrSeparate<["-"], "cxx-isystem">, Group<clang_i_Group>,
   HelpText<"Add directory to the C++ SYSTEM include search path">, Flags<[CC1Option]>,
   MetaVarName<"<directory>">;
 def c : Flag<["-"], "c">, Flags<[NoXarchOption, FlangOption]>, Group<Action_Group>,