Remove some include files reported as unused by clangd.
Change-Id: I39f9d40b9d5bbf040250b41ef258fb8f32dd5c0a
#include "cli/cli-cmds.h"
#include "objfiles.h"
-#include "arch-utils.h"
#include "gdbcore.h"
#include "solib.h"
#include "solist.h"
#include "target.h"
#include "gdb_bfd.h"
-#include "gdbsupport/gdb_vecs.h"
#include "registry.h"
#include "solist.h"
-#include "gdbsupport/next-iterator.h"
#include "gdbsupport/safe-iterator.h"
#include "gdbsupport/intrusive_list.h"
#include "gdbsupport/refcounted-object.h"