Add an option to objcopy to change the alignment of sections.

Add an option to objcopy to change the alignment of sections.

	PR 24942
	* objcopy.c (SECTION_CONTEXT_SET_ALIGNMENT): New constant.
	(struct section_list): Add alignment field.
	(command_line_switch): Add OPTION_SET_SECTION_ALIGNMENT.
	(copy_options): Add --set-section-alignment.
	(copy_usage): Describe --set-section-alignment.
	(find_section_list): Initialise the alignment field.
	(setup_section): Handle the alignment field.
	(copy_main): Handle OPTION_SET_SECTION_ALIGNMENT.
	* doc/binutils.texi: Document the new feature.
	* NEWS: Mention the new feature.