Remove remaining cleanups from compile-object-load.c

Remove remaining cleanups from compile-object-load.c

This removes the remaining cleanups from compile-object-load.c.

gdb/ChangeLog
2018-09-18  Tom Tromey  <tom@tromey.com>

	* compile/compile-object-load.c (struct
	link_hash_table_cleanup_data): Add constructor and destructor.
	Use DISABLE_COPY_AND_ASSIGN.
	(~link_hash_table_cleanup_data): Rename from
	link_hash_table_free.  Now a destructor.
	(copy_sections): Use gdb::unique_xmalloc_ptr.  Remove cleanups.