avr/gas: Write out data to track .org/.align usage.

avr/gas: Write out data to track .org/.align usage.

Adds support to the assembler to write out data for tracking the use of
.org and .align directives.  This data is collected within the assembler
and written out to a section ".avr.prop" (if there's anything to write
out).

This patch does not add any tests.  The next patch in this series will
add a better mechanism for visualising the contents of .avr.prop which
will make writing tests much easier.

This patch also does not make any use of this collected data, that will
also come along in a later patch; the intended consumer is the linker,
during linker relaxation this information will be used to ensure that
the .org and .align directives are honoured.

bfd/ChangeLog:

	* elf32-avr.h (AVR_PROPERTY_RECORD_SECTION_NAME): Define.
	(AVR_PROPERTY_RECORDS_VERSION): Define.
	(AVR_PROPERTY_SECTION_HEADER_SIZE): Define.
	(struct avr_property_record): New structure.

gas/ChangeLog:

	* config/tc-avr.c: Add elf32-avr.h include.
	(struct avr_property_record_link): New structure.
	(avr_output_property_section_header): New function.
	(avr_record_size): New function.
	(avr_output_property_record): New function.
	(avr_create_property_section): New function.
	(avr_handle_align): New function.
	(exclude_section_from_property_tables): New function.
	(create_record_for_frag): New function.
	(append_records_for_section): New function.
	(avr_create_and_fill_property_section): New function.
	(avr_post_relax_hook): New function.
	* config/tc-avr.h (md_post_relax_hook): Define.
	(avr_post_relax_hook): Declare.
	(HANDLE_ALIGN): Define.
	(avr_handle_align): Declare.
	(strut avr_frag_data): New structure.
	(TC_FRAG_TYPE): Define.