gas: free sy_hash, macro_hash and po_hash

	* macro.c (macro_end): New function.
	* macro.h (macro_end): Declare.
	* read.c (read_end, poend): New functions.
	* read.h (read_end): Declare.
	* symbols.c (symbol_end): New function.
	* symbols.h (symbol_end): Declare.
	* output-file.c (output_file_close): Call new *_end functions.