AVR/ld: Use .avr.prop data during linker relaxation.

AVR/ld: Use .avr.prop data during linker relaxation.

Make use of the data held within the .avr.prop section during linker
relaxation in order to maintain the properties of the .org and .align
directives.

In relation to the .align directives, if enough bytes are deleted before
a .align directive then the alignment can be moved while still
maintaining the alignment requirement.

bfd/ChangeLog:

	* elf32-avr.c (struct elf_avr_section_data): New structure.
	(struct avr_relax_info): New structure.
	(elf_avr_new_section_hook): New function.
	(struct elf_avr_section_data): Add relax_info.
	(get_avr_relax_info): New function.
	(init_avr_relax_info): New function.
	(elf32_avr_relax_delete_bytes): Find next property record before
	deleting bytes.  When deleting don't move bytes beyond the next
	property record.
	(avr_elf32_assign_records_to_section): New function.
	(avr_property_record_compare): New function.
	(avr_load_all_property_sections): New function.
	(elf32_avr_relax_section): Load property data.  After relaxing the
	section, move any .align directives that have enough deleted bytes
	before them.
	(bfd_elf32_new_section_hook): Define.

ld/testsuite/ChangeLog:

	* ld-avr/avr-prop-1.d: New file.
	* ld-avr/avr-prop-1.s: New file.
	* ld-avr/avr-prop-2.d: New file.
	* ld-avr/avr-prop-2.s: New file.
	* ld-avr/avr-prop-3.d: New file.
	* ld-avr/avr-prop-3.s: New file.
	* ld-avr/avr-prop-4.d: New file.
	* ld-avr/avr-prop-4.s: New file.