Provide support for Binutils' --no-dynamic-linker option.

[ed]

Summary

GNU ld seems to write a PT_INTERP header into executables containing a
default (read: bogus) value if --dynamic-linker flag is not provided.
LLD is different in the sense that it omits it unless --dynamic-linker
is provided, which seems fair.

Binutils 2.26 added a new flag, --no-dynamic-linker, that can be used to
generate binaries without PT_INTERP. Let's go ahead and also add this
flag to LLD, so that we can invoke the linker in a portable way.

[ruiu]

LGTM

lld/trunk/ELF/Options.td

 def plugin : Separate<["--", "-"], "plugin">;
 def plugin_eq : Joined<["--", "-"], "plugin=">;
 def plugin_opt : Separate<["--", "-"], "plugin-opt">;
 def plugin_opt_eq : Joined<["--", "-"], "plugin-opt=">;
 
 // Options listed below are silently ignored for now for compatibility.
 def fatal_warnings : Flag<["--"], "fatal-warnings">;
 def no_add_needed : Flag<["--"], "no-add-needed">;
+def no_dynamic_linker : Flag<["--"], "no-dynamic-linker">;
 def no_fatal_warnings : Flag<["--"], "no-fatal-warnings">;
 def no_warn_common : Flag<["--", "-"], "no-warn-common">;
 def no_warn_mismatch : Flag<["--"], "no-warn-mismatch">;
 def rpath_link : Separate<["--", "-"], "rpath-link">;
 def rpath_link_eq : Joined<["--", "-"], "rpath-link=">;
 def version_script : Separate<["--"], "version-script">;
 def warn_shared_textrel : Flag<["--"], "warn-shared-textrel">;
 def G : Separate<["-"], "G">;
 
 // Aliases for ignored options
 def alias_version_script_version_script : Joined<["--"], "version-script=">, Alias<version_script>;
 
 // Debugging/developer options
 def save_temps : Flag<["-"], "save-temps">;
 def mllvm : Separate<["-"], "mllvm">;