PR81358: Enable automatic linking of libatomic.

PR81358: Enable automatic linking of libatomic.

ChangeLog:
	PR driver/81358
	* Makefile.def: Add no_atomic=true for libraries that don't depend on
	libatomic.
	* Makefile.tpl: Export TARGET_CONFIGDIRS and create rule to
	add dependencies for libatomic.
	* configure.ac: Add libatomic to bootstrap_target_libs.
	* Makefile.in: Regenerate.
	* configure: Regenerate.

gcc/ChangeLog:
	PR driver/81358
	* common.opt: New option -flink-libatomic.
	* gcc.cc (LINK_LIBATOMIC_SPEC): New macro.
	* config/alpha/linux.h (LINK_GCC_C_SEQUENCE_SPEC): Use LINK_LIBATOMIC_SPEC.
	* config/arm/uclinux-elf.h: Likewise.
	* config/arm/unknown-elf.h: Likewise.
	* config/avr/avrlibc.h: Likewise.
	* config/bfin/linux.h: Likewise.
	* config/darwin.h: Likewise.
	* config/gnu-user.h: Likewise.
	* config/lm32/uclinux-elf.h: Likewise.
	* config/rs6000/linux64.h: Likewise.
	* config/rs6000/rtems.h: Likewise.
	* config/sparc/sparc.h: Likewise.
	* doc/invoke.texi: Document -flink-libatomic.
	* configure.ac: Define TARGET_PROVIDES_LIBATOMIC.
	* configure: Regenerate.
	* config.in: Regenerate.
	* common.opt.urls: Regenerate.

libatomic/ChangeLog:
	PR driver/81358
	* Makefile.am: Pass -fno-link-libatomic.
	New rule all-local.
	* configure.ac: Assert that CFLAGS is set and pass -fno-link-libatomic.
	Use __libatomic_save_CFLAGS__ instead of save_CFLAGS.
	* Makefile.in: Regenerate.
	* configure: Regenerate.

Signed-off-by: Prathamesh Kulkarni <prathameshk@nvidia.com>
Co-authored-by: Matthew Malcolmson <mmalcolmson@nvidia.com>