Add ability for objcopy to insert new symbols into a binary.

Add ability for objcopy to insert new symbols into a binary.

	PR binutils/19104
binutils * objcopy.c (command_line_switch): Add OPTION_ADD_SYMBOL.
	(copy_options): Add add-symbol.
	(copy_usage): Likewise.
	(parse_symflags): New function.
	(need_sym_before): New function.
	(create_new_symbol): New function.
	(filter_symbols): Add code to insert new symbols.
	(copy_main): Process OPTION_ADD_SYMBOL.
	* doc/binutils.texi: Document new feature.
	* NEWS: Add note about the new feature.

tests	* binutils-all/add-symbol.d: New test.
	* binutils-all/objcopy.exp: Run the new test.