gcc/
	Support 64-bit double and 64-bit long double configurations.

	PR target/92055
	* config.gcc (tm_defines) [avr]: Set from --with-double=,
	--with-long-double=.
	* config/avr/t-multilib: Remove.
	* config/avr/t-avr: Output of genmultilib.awk is now fully
	dynamically generated and no more part of the repo.
	(HAVE_DOUBLE_MULTILIB, HAVE_LONG_DOUBLE_MULTILIB): New variables.
	Pass them down to...
	* config/avr/genmultilib.awk: ...here and handle them.
	* gcc/config/avr/avr.opt (-mdouble=, avr_double). New option and var.
	(-mlong-double=, avr_long_double). New option and var.
	* common/config/avr/avr-common.c (opts.h, diagnostic.h): Include.
	(TARGET_OPTION_OPTIMIZATION_TABLE) <-mdouble=, -mlong-double=>:
	Set default as requested by --with-double=
	(TARGET_HANDLE_OPTION): Define to this...
	(avr_handle_option): ...new hook worker.
	* config/avr/avr.h (DOUBLE_TYPE_SIZE): Define to avr_double.
	(LONG_DOUBLE_TYPE_SIZE): Define to avr_long_double.
	(avr_double_lib): New proto for spec function.
	(EXTRA_SPEC_FUNCTIONS) <double-lib>: Add.
	(DRIVER_SELF_SPECS): Call %:double-lib.
	* config/avr/avr.c (avr_option_override): Assert
	sizeof(long double) >= sizeof(double) for the target.
	* config/avr/avr-c.c (avr_cpu_cpp_builtins)
	[__HAVE_DOUBLE_MULTILIB__, __HAVE_LONG_DOUBLE_MULTILIB__]
	[__HAVE_DOUBLE64__, __HAVE_DOUBLE32__, __DEFAULT_DOUBLE__=]
	[__HAVE_LONG_DOUBLE64__, __HAVE_LONG_DOUBLE32__]
	[__HAVE_LONG_DOUBLE_IS_DOUBLE__, __DEFAULT_LONG_DOUBLE__=]:
	New built-in define depending on --with-double=, --with-long-double=.
	* config/avr/driver-avr.c (avr_double_lib): New spec function.
	* doc/invoke.tex (AVR Options) <-mdouble=,-mlong-double=>: Doc.
	* doc/install.texi (Cross-Compiler-Specific Options)
	<--with-double=, --with-long-double=>: Doc.

libgcc/
	Support 64-bit double and 64-bit long double configurations.

	PR target/92055
	* config/avr/t-avr (HOST_LIBGCC2_CFLAGS): Only add -DF=SF if
	long double is a 32-bit type.
	* config/avr/t-avrlibc: Copy double64 and long-double64
	multilib(s) from the vanilla one.
	* config/avr/t-copy-libgcc: New Makefile snip.

From-SVN: r277908