Get rid of now unused plugin-list option

Author: dmpots

lldb/source/Commands/Options.td

@@ -683,11 +683,6 @@ let Command = "platform shell" in {
     Desc<"Shell interpreter path. This is the binary used to run the command.">;
 }
 
-let Command = "plugin list" in {
-  def plugin_info_exact : Option<"exact", "x">,
-                          Desc<"Do not add implicit * glob around plugin name">;
-}
-
 let Command = "process launch" in {
   def process_launch_stop_at_entry : Option<"stop-at-entry", "s">,
     Desc<"Stop at the entry point of the program when launching a process.">;