Add more targets to the list of architectures not supporting format changing during...

Add more targets to the list of architectures not supporting format changing during linking.  Fix seg-faults triggered when this is attempted.

	PR ld/21884
	* testsuite/ld-elf/pr21884.d: Add AVR, HPPA, IA64, M68HC1x and
	SCORE to list of targets not supporting file format changes during
	linking.
	* testsuite/ld-unique/pr21529.d: Likewise.
	* emultempl/avrelf.em (_before_allocation): Skip for non-ELF
	output formats.
	(avr_elf_create_output_section_statements): Fail if the output
	format is not ELF.
	(avr_finish): Do not access the ELF header in non-ELF format
	output bfds.
	* emultempl/m68hc1xelf.em (_before_allocation): Skip for non-ELF
	output formats.
	(m68hc11elf_create_output_section_statements): Fail if the putput
	format is not ELF.
	(m68hc11elf_after_allocation): Skip for non-ELF output formats.