re PR target/78093 ([avr] New variable attribute "absdata" and option "-mabsdata" to enable LDS / STS on Reduced Tiny)

gcc/
	PR target/78093
	* doc/invoke.texi (AVR Options) [-mabsdata]: Document new option.
	* config/avr/avr.opt (-mabsdata): New option.
	* config/avr/avr-arch.h (avr_device_specific_features):	Add AVR_ISA_LDS.
	* config/avr/avr.c (avr_encode_section_info) [AVR_TINY]: If
	-mabsdata & symbol is not progmem, tag as AVR_SYMBOL_FLAG_TINY_ABSDATA.
	* config/avr/avr-mcus.def (attiny4/5/9/10/20): Use AVR_ISA_LDS.
	* config/avr/gen-avr-mmcu-specs.c (print_mcu): Print cc1_absdata
	spec depending on AVR_ISA_LDS.
	* config/avr/specs.h (CC1_SPEC): Enhanced by cc1_absdata spec.
gcc/testsuite/
	PR target/78093
	* gcc.target/avr/torture/tiny-absdata-2.c: New test.

From-SVN: r242379