re PR target/54607 ([avr]: Canadian cross build fails because gen-avr-mmcu-texi.c is compiled with the wrong compiler)

	PR target/54607
	* config.gcc (tm_file,avr): Add avr/avr-arch.h.
	* config/avr/t-avr (gen-avr-mmcu-texi): Use CC_FOR_BUILD to
	compile.  Don't depend on TM_H.  Use CFLAGS_FOR_BUILD.
	* config/avr/avr.h (avr_arch, base_arch_s, mcu_type_s): Source out
	to...
	* config/avr/avr-arch.h: ...this new file.
	* config/avr/gen-avr-mmcu-texi.c: Include avr-arch.h, stdio.h,
	stdlib.h.
	* comparator: Make letters smaller than digits.
	* config/avr/avr-devices.c: Don't include headers if used in
	gen-avr-mmcu-texi.c.
	* doc/avr-mmcu.texi: Regenerate.

From-SVN: r191390